He's already admitted as much, there are minor changes to what he'd planned but the show's ultimate ending is very similar to what he'd written in his notes. Bran becomes the king in the South for some reason, Samsa queen in the North, Aria goes off on an adventure and John Snow goes back to the night watch, having grown exactly 0% after they fucking murdered him, which consequently is where the books leave off.

So if you take that ending as canon, that John Snow dies and so Westeros falls, I gotta say it's a brave ending.