Yeah, he told David and Dan (main show runners) how he wants to story to go and what he wants as endgame and stuff. I'm pretty sure they also know who Jon Snow's mother is, too, but I'm not -certain-.

Dranzer, the second half of A Storm of Swords gets so much better.
Spoiler:
Don't let the Redd Wedding dishearten you. The North Remembers!