The author already said from the extra pages that there was no assurance that Souma died or even lived. But FOR ME, as I re-read this again, it seems he will live on because he has the reason and it's Masataka.
from the author's note, the way author said it means souma is alive "because there is no way a person will die if he will to live" and the stab wound isn't really critical unless he loss a lot of blood
The author already said from the extra pages that there was no assurance that Souma died or even lived. But FOR ME, as I re-read this again, it seems he will live on because he has the reason and it's Masataka.