Queer witty banter writer Bruce Villanch claims to have been friends with Luther and that Luther confided in him that he was gays. And really, from songs like "Secret Love" to him referring to Fonzie Thornton as
in the "thank you" notes of one of his albums, to his speech patterns and love of sequins...my "best friend" - don't write a book, ha ha
It's currently on his Wikipedia page, but even the well sourced information about his sexuality often gets taken out by people who cannot handle the truth.