Except Gambit wasn't on the cover of the X-Men Annual #14, that probably was a big influence with what book became the market favorite.
Besides, from the text we now see inside Avenging #9, it's without a doubt Marvel acknowledges Captain Marvel #1 won't come out until a week after Avenging #9 and even makes note of it.
OK, I'll admit it. I've seen this cover a million times, but never read the book.
Who is that on the cover that kind of looks like Gambit, but maybe a cyborg version?
Oh, and this Marvel Wiki (if that counts for anything) still lists this as Gambit's first appearance.
http://marvel.wikia.com/Uncanny_X-Men_Annual_Vol_1_1990