Maybe. But you don't need that many to rebel to throw a spanner in the workings of Brexit. Simply debating the merits of a hard Brexit for a few weeks in the Parliament could do wonders to popular opinion on Brexit, limiting Brexitards to deplorables only.
SNP has several shots at stopping a hard Brexit, if not Brexit outright.
Corbyn has Labour not to oppose Brexit, but put in amendments that would complicate a hard Brexit. For Brexitars, that could well be worse than Labour trying to stop Brexit - they can't divide the country that way. Plus of course, that's what he said before the debate. Given the nature of the debate he could easily declare Tory plan unworkable and destructive for UK and have Labour vote against it. He could then claim Labour wasn't against Brexit, but that Tory incompetence ensured Brexit was a failure and he couldn't support that. If that happens even a minor revolt in Tory ranks could have the Parliament reject the legislation that allowed Theresa to trigger A50, resulting in a political crisis.
In light of that, his statement that he will not oppose Brexit on principle was probably the best thing to say. It leaves all of his options open. Whether he will use them to stop this idiocy, reduce the scope of the idiocy or not exploit it at all remains to be seen however.
Defeatist mentality will get you nowhere - even if you're right in everything it's still the wrong way to go.
McHrozni