I don't think Martin is influenced by fan theories because he refuses to read them. I'm sure fans have verbally told him theories that made him think "that's interesting" but overall the longer this goes the longer it's clear how meticulous he is as a writer/planner. Yes he has described himself as a gardener type writer, but even the earliest books have clear foreshadowing or introductions that come to fruition books later (ie he planted the seeds). I was watching a theory vid recently that pointed out Marwyn The Mage is not only referenced in the first book, he is brought up to Dany. And now he's traveling to meet her. I had totally forgotten that he was established in the first book. Somewhat connected to that, in the second book there's a reference to "Urrathon Night-Walker" reporting that glass candles have activated...and the theory that he's almost certainly Euron Greyjoy.
He's really good at what he does. For years I was tuned out of all book related stuff. I watched GoT but stopped looked at theories. I remember when the Grand Northern Conspiracy came out and that shyt was so exciting. But that was almost a decade ago. Same with some of the other theories that emerged from ADWD, like the Stannis/Night Lamp theory on how he'll defeat the Freys. House Of The Dragon inspired me to get back into theories. But man...knowing the book probably won't come out next year will likely kill my excitement again.
Same with HoD’s, I had fully moved on, on some fukk this shyt, I’m never going back, I even watched the first episode of HoD and left it alone, I didn’t think it was great at first, but then my wife really wanted to watch it, so I caved, and was happy I did. They really resuscitated the series with how well they did it. The new mistborn book comes out next week, and I just finished a relisten of the series in preparation, last week, so I said fukk it and decided to redo Fire & Blood. I forgot how addicting the Planetos can be. On another note, I just want to shout out my favorite author in the genre, Tad Williams, his shyt is not for everybody, but that’s my goat, and if anybody is looking for a series and has some time, Memory, Sorrow, and Thorne is goated imo, and he ran it back a few years ago with “The Last king of Osten Ard” series taking place about 25/30 years later