They can but most don't. It is like any addiction. You become obsessed with it and it is all you focus on. Unfortunately, sexual behavior is reinforced by one of the most powerful positive reinforcement mechanism that humans have.
So in other words most gays and child molesters cannot be reformed but a few can be cured.
Again would you let someone who claimed to be an ex child molester baby sit your children?
And would you be happy if your daughter married someone who claimed to be ann ex gay?