There will only be 13 more episodes of Game of Thrones after Season 6


-Season 7 will have only 7 episodes.

-Season 8 will only have 6 episodes

They are not 100% sure if its going to be 13 episodes yet, but considering they're talking to Variety about its probably pretty legit and the final number probably wont be that different from 13 even if it does get changed.

SOURCE