Looking at Population Change data derived from version 6.2 of the Penn World Tables.
It appears that the population of Kuwait declined by 55.46% in 1991, only to increase 48.64% in the following year.
I’m inclined to think of this as measurement error, not a mass exodus following by a mass return after the invasion. But that’s mainly because I think we would have heard if fully half of the population of the country had left.
Anyone have any information otherwise?