I always thought he kept them up his sleeves. I’ve never seen Gambit have to go through his pockets looking for his cards. That would be hilaire though!
“Hey mon brave, jes’ gimme a second, no? I’m lookin’ f’r my cartes. Dey’re somewheres in ‘ere. In one o’ my pockets. Ima fin’ dem, den we c’n fight, yes? Bada Boom! Gumbo. Tres cajun, no?”