Is he gay or maybe a little bi? Possibly! Does he have a hard-on for Caius? I personally don't think so.
I don't think the game provides us with any even remotely definite clues as to what his sexual orientation is, and any attempt to find these clues tells us more about the sexual desires or fears of the person looking for them.
everything is wrapped in gray
i'm focusing on your image
can you hear me in the void?
Noel can't be gay... he wouldn't be interested with someone who has as bad a fashion sense as Caius.
Nah, he's too crazy about Yuel to be gay.
Also, really, Noel romantic for Caius? That's as bad as the Vanille being romantic for Fang...thing.
I like Kung-Fu.
I was extremely greatful to the writers because of Noel and Serah's relationship being completely plotonic, it felt more real. If Noel even flirted with Serah in any way it would've been a really dumb move considering the situation they're in. And realistically in a tribe, where males are supposed to actively assert their alpha male qualities in a fight to the death to become the Seeress's guardian, I don't see homosexuality working in that environment at all.