Martin says some people have.
According to the Telegraph, while the author was at the Edinburgh International Book Festival, he admitted that some fans have figured out the ending to his books.
“Some of the theories are right,” he said. “At least one or two readers had put together the extremely subtle and obscure clues that I'd planted in the books and came to the right solution. So what do I do then? Do I change it? I wrestled with that issue and I came to the conclusion that changing it would be a disaster, because the clues were there. You can't do that, so I'm just going to go ahead.”
Martin has released five books in the “Song” series and the sixth and seventh books are still being written. Martin’s editor Anne Groell recently said that she was “begin[ning] to wonder” if an eighth book would happen and after the quote sparked fan speculation, Martin told Entertainment Weekly that he was still planning on seven books but to “get back to me when I’m halfway through Book Seven and then maybe I’ll tell you something more meaningful."
The HBO series “Game of Thrones” concluded its fourth season earlier this summer.