Yes, Gambit is an omega-level mutant.
Remy's powers grew out of control and Sinister performed surgery on him to make his powers remain alpha level before they went out of his control.
What level Gambit's powers could truly be without that surgery was revealed with the appearance of the New Sun. The New Sun character was an alternate version of Gambit that had reached his full potential and had destroyed his own world by burning it as though he were a star. This version of Gambit, overwhelmed by guilt and self-hate, traveled to several different realities to kill each version of himself before they made the same mistake he did.
So, New Sun was definitely Omega and the mainstream version of Gambit has this ability fully restored by Sinister. At the moment it is presumed that Remy burned out his powers defeating the New Sun. However, Gambit has been de-powered before and eventually his powers came back. Also, when Gambit's abilities are limited his body manifests its mutation in different forms to compensate which only an Omega would be capable of. One of many examples is when Gambit was blinded and he could see the future by reading playing cards (ie. manipulating time, space & energy is something both he & New Sun were both capable of).
Thus, Gambit *is* an Omega level mutant and his powers *may* be burned out for now to a controllable level but they can resurface in the future.
Let's hope he can learn to control them if they do! ;-)
P.S. Check out Gambit Annual 1999 - lots of background there.
Yes. New Sun is an Omega, especially if he beat the Pheonix. But... Gambit actually may be on his way to becoming an Omega as well...
I mean it is just speculation on my part, and if you haven't read the last Gambit title run and don't want SPOILERS!!! STOP READING HERE!
In the last issue of the 2012 Gambit series something happens that could open the door to Gambit getting back his full power potential. Keep in mind, his powers were only limited because he begged to Sinister to limit them. This was accomplished by removing a key portion of his brain tissue. This tissue was restored later by Sinister when Remy traveled back to the past. However, this is still just recently repaired brain tissue. So when he fought the New Sun in the final showdown and poured everything he had into it, he burnt out, likely damaging the patchwork tissue in the overload.
This makes what happened in issue 17 of the latest series very interesting. Because Remy gets shot in the head. Just before he dies though the knight Faiza Hussain uses her powers to heal him and extract the bullet. After this he gets up and spits the charged bullet at his would be killer, dragon breath style, and the overblown explosion makes him ask back to Faiza if she was sure she had put him back together right.
So... if her healing of his head did not only repair the damage the bullet had done, but also old damage, from surgeries and burn outs..... it may only be a matter of time before Gambits true power starts to surface. 0_0