what I did was become close to the openly homophic person, come out to them. They like you so they reconsider their opinion of gay people. Works for anti-furries and furries too.
Like most phobias, the most effective treatment is exposure therapy. Start by exposing the homophobe to mildly gay things, like attending Broadway musicals and dressing extravagantly. Once they're comfortable, you can progress to majorly gay things, like posting on c/196.