Afaik, that depends on how old the patient is. Chances go way down pretty quickly, but there have been near full recoveries surprisingly late. Read a particular case study of a young man with traumatic brain injury where the whole case study has you keep going "this man is so done for" and yet he advised the doctors on the final paper. Mental.

Here, found it: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3902071/

Wouldn't want to be a doctor making such a grave call with such a lack of certainty. Hate idea of giving up on someone who would have made it, but also of keeping a family from moving on for so long for nothing at all, or a patient who won't ever progress beyond opening his eyes and flinching again. "Waking up" is a multistep process, and you can get stuck on any step of the ladder, incl. those where you are not conscious, or can't move. (Ideally, both together, being stuck on just one truly sucks. E.g. locked in syndrome. Or vegetative state patients who are not yet conscious, but start screaming and screaming.)