So, uh, trans guy, here, which I’m not sure is your target response pool for your question, but does allow me to offer some front-lines feedback as to whether gay cis men will date and/or hook up with trans men, before or without or over the course of medical transition.
*I see this on reddit, but the average guy does not start with "So, uh,...", a few words in and already tripping over female expression patterns. She follows with an essay, where I would have ended with, "No, they do not and if only pay the merest of lipservice in order to extract themselves from an awkward social situation and make a quick exit."*
A few gay cis men are really freaked out by the very idea of a trans guy, and will absolutely not date or hook up with him, on any account, ever. That’s not necessarily because they aren’t attracted to him; it’s more because they’ve learned a single way that being gay is Supposed To Be, and when you’re already the “wrong kind” of sexual, the idea that you might be the wrong “wrong kind” of sexual can feel that much less tolerable. These guys, unfortunately, might be kind of mean—or they might just shut down, or try very hard to be very nice, but in all the worst possible ways. It’s a them-thing, not a trans-guy-in-question thing.
*Freaked out? I would argue more extremely annoyed, that they got catfished by an Aiden, who will A) turn into a blubbering mess the second she smells rejections and B) may very well fuck you over by poisining the well if she recognizes you from the same local scene with passive-aggresive media screeds. Yes, we will shut IT down, as most guys will not take this shit. COPE#1 She copes by placing the blame on our narrow view of SEXUALITY, again showing how they will interchangably use Gender/Sex, because to them it is the same, entirely socially constructed.*
Some gay cis men are attracted specifically and exclusively to male-normative primary and secondary sex characteristics, in a configuration that wouldn’t be present for a trans guy who hadn’t been on hormones and had multiple surgeries. Those guys won’t be on the table for the protagonist of your question—and while they might find numerous hypothetical or future iterations of him attractive, they also might not. Oh, well. None of us were ever going to turn everyone on.
*Some? How about all of them? Perhaps a handmaiden here or there, but I sincerely doubt that when push comes to shove they will touch you. The others are chasers bisexual or straight who know that you are desperate easy targets. Male-normative seems very vague, as I would hazard that you are angling at a gay male standard, but hey it does sound smart, so fuck it! COPE#2 "and while they might find numerous hypothetical or future iterations of him attractive, they also might not. Oh, well. None of us were ever going to turn everyone on" Perhaps in very rare circumstances the fantasy might be erotic enough for the sake of novelty, otherwise NOT GONNA HAPPENS love! Gotta love that last part, they gotta count themselves lucky if they are going to turn anyone on.*
Some gay cis men assume—right along with most of everyone else, to be fair—that they’re attracted to a particular slate of male-normative primary and secondary sex characteristics, which line up neatly with the gender identity and gendered history also shared (more or less) by cis men… until they encounter a reason to question that. And then they find that some of those things are really central in their attractions, but others aren’t. Or—more often than I had expected—that they’re less drawn to specifically male embodiment, at all, than to particular kinds of masculine presentation and/or self-understanding.
*Again, some? There is no assumption, it is our standard wiring and that shit ain't changing post-partum, but thank you world for bringing us conversion rhetoric from inside the house! A reason the question: you mean annoying manlets causing a scene and in female fashion gossiping your reputation into the dirt if you do not mindelessly echo affirmation?
Yeah, we are drawn to a male body and yeah some like em more feminine and quite a few prefers a guys guy who enjoys a dick. Which you will never have or delude yourself that your laughable mimicry is an acceptable substitute*
Relatively few people really talk about it, I suspect because they, themselves, don’t always know what to make of it—but there have always been gay men who will bottom for a lesbian with a strap-on—or factory-standard penis—and there have always been lesbians who are happy to oblige. We don’t have a terribly refined spectrum of consensus language around sexuality, is the thing. So we’ve ended up with this mish-mash of sexual role preferences, and gender-inflected attraction, and bodily preferences, and even contextually socially acceptable gendered presentations in ourselves, that all hide in the category “gay,” and that we’ve mostly taken for granted all line up in precise and readily-identifiable symmetry. Sometimes, though, they just… don’t. I think that’s good news; certainly, it’s interesting news. But it does make it hard to predict how any given person will respond, based on a one-word description of their sexuality.
* "...there have always been gay men who will bottom for a lesbian with a strap-on" Oh really? Would love to meet em. Most guys I met enjoy toys, but I only know em preferring getting pegged by the real thing over a fucking dildo, also usually both guys also enjoy pleasuring the other, a hunk of plastic does not feel much. Also LMAO at "factory-standard penis". These people really do view the entire Human Body like a fucking PC you can strip for parts."*
Which brings me to… some cis gay guys have, in fact, thought all of this out, and already know thet they’re drawn to some aspect/s of manhood or masculinity that aren’t exclusive to male-normative embodiment. They’re a little thinner on the ground, for the same reasons that people of any gender and sexuality who’ve thought that deeply about sex and gender are thinner on the ground. But they exist.
*As I already pointed out, most of us figure out pretty quickly what we like. It does not include you, beyond platonic relations Go Home AIDEN.*
Anyway, my short answer for you is: sure. My experience, to date, strongly confirms that some gay cis men will date—and be happily and effectively sexually active with—a trans guy who hasn’t been on hormones or had surgeries. And some is as good as it gets, regardless of gendered history and approach to transition. Some gay cis men will also date a trans guy who has been on hormones, but not had any surgeries. Hilariously enough, see also my final couple of paragraphs, I haven’t actually been with a cis guy, in any sense, since having chest surgery—but I presume, and in a few cases have been made aware that they wouldn’t be any less interested than previously, lol.
*The best part! Yes, Gays do want us, even if I have nothing to present that I could persuade you with! BUUUUUUUUUUUUTTT*
(In case this is a personal question—or on the off-chance that it’s not, and that you intended to include gay trans men in the population you were asking about—I’m going to add: with few, though notable, exceptions, I’ve been happier in relationship with other trans guys, than with cis guys. Like, commonality of experience is nice, but also. Less weirdness and angst about bodies—and I used to say it with a lot less confidence and a very considerable edge of defensiveness, but, man. With the benefit of a few more years of experience, and a little more practice not depending on other people’s sexual attraction to validate my gender? There really is a lot to be said for a dick that is size-variable; always hard, for as long as you want it to be; and can be stashed politely in a box under the bed, when it would get in the way. I wouldn’t turn down a guy with a factory-standard or surgically-built dick, on principle—there are things that are nice about those, too—but if we’re talking genital preference, my top pick is a rainbow pour of dual-density silicone.
*I pretty much date other AIDENS for these reasons (insert anything, if only to hide the fact to myself to no honest and true FAG wants my "fronthole" and mishshapen pectoral region) YES I AM VERY HAPPY WITH MY TOTALLY MANLY MAN OF AN AIDEN! ALSO DILDO'S ARE WAY BETTER THAN THOSE STUPID "FACTORY-STANDARD PENISSES"* 
I’d also usually rather date self-identified bi guys, than gay guys. This isn’t because of the fucked-up thing cis people sometimes like to say about “well, YEAH, because YOU’RE THE BEST OF BOTH WORLDS.” It’s because bi guys have, for the most part, already dealt with whatever internalized weirdness they might once have had about not being “gay enough” or “straight enough”. That improves the odds that they aren’t going to be weird and stiff and panicky with the trans guy who is flirting with them; and that makes everyone’s evening better.)
