George R.R. Martin’s main tactic with The Winds of Winter is to delay everyone. In January 2017, he said of the sixth A Song of Ice and Fire book: “I think it will be out this year. (But hey, I thought the same thing last year).”
Martin has said the new book will begin with “a big smash with the two enormous battles”. The battles he’s referring to are Yunkai’s siege of Meereen, and Stannis’ siege of Winterfell. He’s also promised “more deaths… more betrayals… more marriages. A lot of stuff is happening at The Wall.”
He says, also, that Book 7, A Dream of Spring, will be the last in the series but the story is so huge there’s absolutely no guarantee the series will finish up in just two books — even if those two books get written. It was originally meant to be a trilogy, after all.
I certainly hope he actually finishes A Song of Ice and Fire.