I hardly ever make political predictions, and I may very well be wrong here, but I predict that if the Moggites challenge TM's leadership, and that goes to a vote of Tory MP's, I think she will win.
There are three factions amongst Tory MPs - Moggites (swivel-eyed ultra brexiters at all costs), TM loyalists (who may be looking to advance their careers) and Remainers (who will reject any brexit but not vote against TM).
She would survive, and carry on regardless, but at some point she would have to ensure that we did not jump off that cliff of a no-deal brexit.
It does not matter how many times she has said she would not allow a People's Vote under any circumstances, if that is what Parliament votes for, it will happen.