There is nothing to suggest that Cameron Dallas is homophobic. There have been a lot of rumours about him being gay, and he is often asked this via fans on Twitter. Although he has made it quite clear that he is straight, he has never done so in a derogatory way to the gay community, and has never suggested he has any problems with gay people.
His close friend and fellow Vine star Nash Grier was recently in trouble for making negative comments about gay people and AIDS on his Twitter, but there is absolutely nothing to suggest that Cameron shares any of these views.
There is no doubt that a large section of the demographic of Cameron's fans are gay males, judging by the amount of gay "fanfic" about him on the internet. Although a lot of it is about him and Nash Grier, who is perhaps not as impressed if his homophobic comments are anything to go by...