It is JW dogma that gay people can change.
The belief is based (at least) on the letter claimed to have been written by the Apostle Paul to Christian congregation in Corinth, part of which states:
"... Don’t you realize that those who do wrong will not inherit the Kingdom of God? Don’t fool yourselves. Those who indulge in sexual sin, or who worship idols, or commit adultery, or are male prostitutes, or practice homosexuality, ... none of these will inherit the Kingdom of God. Some of you were once like that. But you were cleansed; you were made holy; " (1 Cor. 6: 9-11 NLT)
There seems little doubt that the leadership firmly believes that if you are same sex attracted, you can change, as we note that the top leadership has included people who can be described as same sex attracted, but were (supposed to be) not leading an active sex life.
It is worth noting that 'homosexuality' the English word denoting same sex attraction, and which is now applied to people who are seen as 'gay' whether or not they engage in same sex behaviour.
In biblical times, there does not seem to have been a word to describe a latent tendency toward same sex attraction, but only action words. words describing what people did.