At the beginning of Dragon Ball GT, Pilaf is an elderly man.
During Battle of the Gods, which takes place roughly 15-20 years before the beginning of GT, Pilaf is reduced to a child, however it should take longer than 15-20 years for Mai, Shu and Pilaf to re-age to the point they are at the beginning of GT.
So, which is canon?
GT isn't canon
The special episode with Vegeta's younger brother has already replaced GT as the new canon.
The sweet sweet tears of butthurt dragonball fanboys
GT is in another universe/timeline. The last movie stated that for new random shit to happen.
Who the fuck cares about Pilaf? Garlic Jr. is the best.
Even GT was better than the Garlic Jr. Saga.