What are you defining as "homophobia"? Only actions or also rhetoric? Such definition is not always agreed with ease, I hope we might need such definition clear before prison.
These are no answer to definition, however. Is Christian saying "gay is wrong" punish with jail? Is Christian saying "do bad things to gay people" punish with jail? Is Christian saying "no marrying for gay people" punish with jail? Some combination of some?
None, as long as they don’t try to agitate children. Again, same as with drugs or alcohol. (Well, “do bad things” is a crime, but looks the same of you replace homophobia with any other reasoning.)