Is Johnathan Knight gay

Yes, he was outed by his ex-gay lover Kyle Wilker:

Jonathan and the 27 year-old Brazilian model Kyle have only dated for 18 months but it was an intense relationship. Kyle says: "We had a wonderful relationship. I was in love with him and I believe he was in love with me." Kyle also reveals Jonathan likes to stay home and be quiet: "I call him a straight guy who happens to be gay."

Johnathan Knight for those who don't know was a member of the New Kids on the Block, boy band.