Honestly, I'm not getting any strong gay vibes from the way the character has been written thus far. He has a long history of hitting on women & failing at holding one. Not saying that a talented writer couldn't out him as a bisexual (or even as a sexually confused gay man), but so far he's seemed mostly straight to me.
I think that Iceman simply has gay appeal, even if he isn't actually gay himself. He is, after all, a young, fun, sexy & nearly nude male with no prominent female love interests, so I would imagine that he's the type of character who appeals to many gay readers.