Just now encountered this thread for the first time and I'd like to weigh in. Firstly, I'd like to believe that Capcom deliberately avoids mentioning anything about Chris's love life because frankly it's not important in the context of any of the video games, considering he's always fighting for his life. However, I don't believe that that is the case. I'm guessing it's more of a business strategy than anything. Regardless of whatever his true sexuality may be, he's become a large sex symbol for women and men alike. To confirm his sexuality in any way would harm his image for someone.
Additionally, they're incredibly indecisive when it comes to anything relating to their characters. Fans argue about characters' sexuality, relationship status, significant others, and in some cases even whether they are living or dead. This is something that many of us seem to enjoy debating, and it also keeps us interested in the characters and their lives. This wouldn't be possible if Capcom explicitly stated certain things about these characters, which is why I believe they will continue to leave these issues unaddressed, as it leaves more room for us to imagine and debate our own personal beliefs on the subject.
Regarding my personal thoughts on Chris's sexuality, I would like to start by saying I hate the idea of Chris and Jill being together. I like both characters, and I mean no offense to people who do see them together, but I can only see it as another situation where *insert male lead* gets together with *insert female lead* because they're supposed to and that's just how it goes (I could argue for pages as to why I absolutely hate Kirito x Asuna for that exact reason but this is neither the time nor the place). Now that we've got that out of the way, I personally believe that Chris is bisexual. I'm not going to pretend that I have any proof, because frankly there is none, but I just get a bisexual vibe from him. I don't however believe he's ever been romantically involved with, nor interested in any of the other characters we've seen. I don't believe he's gay because as someone pointed out, while any information that suggests he is interested in women never made the final cut and therefor is non-canonical, if the creators believed Chris to be gay they wouldn't have considered it in the first place. But then again, I'm pretty sure they didn't even know Alex Wesker's gender until they started working on Rev2, so anything's possible.