Personally, I think you should distance yourself from him and here’s why.

My Wife fell in love with her gay friend when she was in high school and she really thought she could turn him straight but the closer she got to him the more it hurt her and all her friends tried to tell her tried to tell her she was wasting her time but she wouldn’t listen to them. He ended up moving away to Perth and he chose not to stay in contact with her because he knew she would always want to be more than friends with him and it was hurting her and she told me him moving away was the best thing for her.

It is up to you what you choose to do but unless he is Bi I can't see you changing this guy anymore than my Wife tried change her gay friend.