Could be, but not necessarily. I'm guessing GRRM gave them a checklist, that included character deaths and other major events.
Or am I speculating crap here?
Reminds me of Dragon Ball Super. Akira Toriyama gives an outline and assists with storyboards, but ultimately the anime and the manga are free to do whatever they want for about 80% of the story.
On one hand I hate having to watch this abbreviated fan fiction weekly. You can tell just how much DnD hate this series and how much they're dying to get it over with. On the other hand it means there's less of this trash I have to watch, so maybe I should be happy.
get it off ya chest.