It sounds as if Channing Tatum is confirmed to play Gambit for most likely a standalone X-Men film as producer Lauren Shuler Donner confirms Tatum in the following video.
Donner is asked who would play Gambit to which she replied, "It is Channing."
Donner is then asked, "So that is confirmed," and she replies, "Yes."
Donner then goes on to describe why Channing Tatum will play a good Gambit.
"Well, you know he's a rogue. Channing. He's a rascal just like Remy Lebeau. He can handle the action, we all know that. He's got a really good heart. I know him personally. I did a movie with him. I think he'll be great. He'll be great for Gambit. He's a Southerner, too. He's not from New Orleans, but he is a Southerner and he understand that world. You know Gambit loves New Orleans."