She is, but she cannot survive a major defeat on policy; IF pro-EU rebels help defeat the government on Brexit, then she is a PM defeated by her own party. She could not hang on (well, it would be hard as she would have zero authority) and some of the vocal pro-Brexit types would then have to step up, or seem all talk and no action (?).
That is entirely possible, that they will have to put up or shut up.
It's up to you to judge whether PMTM is playing that game or is not.