Lets clear up one big misconception about the term "autotune"
Autotune has been in music since before T-pain ever released a track
Every sound engineer autotunes the vocals to match up with the desired key.
What T-pain did was use autotune in a way that you are not supposed to use it for. He did not use it to match a barely off key to the desired frequency.
He used to to take a G and turn it into a B. T-Pain purposefully distorted it to have a desired robotic sounding effect. He did not turn a G into a B because a G was the closest he could get to a B while singing naturally. He's not THAT trash
He did it because he liked the distorted sound
This whole notion that he introduced Autotune to music is asinine. If you have ever heard any studio recording of any vocals from the late 90s onward, you have heard autotune.
And with the increased processing power of modern computers, Autotune is not relegated to studio recording. It can be done live, and is done live.
TLDR: Once again.. every singer in every genre uses autotune