He is younger than you, and he is surrounded by people who are homophobic. He is at a confusing time in his life, and he has many many influences and so much pressure. Give him time, let him figure himself out, and don't pressure him yourself. It'll work out how it's supposed to, so just hope for the best. One way or another, he'll probably be bi or gay, and once he truly finds himself(which may not be until he graduates and is away from the high pressured situations) is when you'll find out that it'll work out.