A Channing Tatum-led Gambit movie, whether it’s a mob movie or a romantic comedy, could still work even if the X-Men franchise was rebooted, but it’s possible Marvel and Disney would prefer putting out a more conventional, ensemble X-Men movie first.
In any case, considering that the character’s only theatrical appearance so far has been in the critically-derided X-Men Origins: Wolverine, Rupert Wyatt’s Gambit movie sounds like it would have treated him much better.
With only days remaining until the Disney and Fox merger closes, leading to (among many other things) the X-Men and Fantastic Four properties finally residing at Marvel Studios, it’s unclear if Gambit will ever be made.