How should I befriend this guy and be a supportive friend?

Hey guys, so there is this guy at my school in which I have many classes with (Orchestra, Science, the like). He is a jock but is EXTREMELY smart and friendly, compared to other classmates. Recently he seems to be somewhat taunted (though nonchalantly) by fellow classmates, including my friends for being accused of being gay. It is kind of obvious that he is considering ALL his friends are guys and he never seemed to ever have a friend or relationship with a girl (Along with the fact that his mother for some strange reason told my friends that his favourite show is Glee, though I don't see how this makes him gay). He sits next to me in all classes, so I was thinking that I could befriend him and give him a bit of friendly support, which he most certainly is in need of.

So how do you think I should do this and become a supportive friend? We are already kind of friendly acquaintances because we do talk to each other during classtime, but not really anything further than that.

Any ideas are appreciated, thank you.