Is Kuwait's population declining or growing?

The overall population is growing, and keeping in mind that only about 1/4 of the country's population are actually Kuwaiti, not all of this population growth is of Kuwaiti citizens. You are not automatically a citizen if you are born there.

Also keep in mind that Kuwait is missing a large portion of an entire generation of men that were killed during the Iraqi Invasion in the 90's.

Growing. By about 7-8% per year

Yes, Kuwait is.

It is growing and it is growing because there are no laws saying how many children each couple is allowed to have. I think they have 2.34 children per couple which would indicate a growing population.