Certainly Martin is aware of Tolkien's Silmarillion (in terms of both content and concept) and references it multiple times in interviews, along with other of Tolkien's works, including his essays. I think it's fair to say that if he's not read it cover-to-cover then he's at least skimmed it.

Tolkien gave us all these histories all these appendices and genealogies and everything was was routed and it seemed as real as England or France or Germany when you when you read these things and since then that's become the style for epic fantasy. I see a lot of fantasy readers now expect they expect a fully real 'secondary world' as Tolkien called it and so certainly that's what I set out to creating in Westeros. Now some of this is a magician's trick [but] it really wasn't with Tolkien. You have to consider that Tolkien is, was a very unusual writer, I mean he was a linguist and a philologist, spoke Old Norse and Old English, he was fascinated by myth you know he, the story was almost secondary to Tolkien. He spent years creating his Silmarillian and never published in his lifetime and the Lord of the Rings and The Hobbit were like the stories set in the world he created, but for him the world creation and the creation of languages was almost primary. If you look at it like an iceberg he, you know, they say that three-quarters of iceberg is hidden below thoughts below the surface that was certainly true [in his case]

And

My editors said, “This is going to ruin the entire concept of the book, we already spent the entire art budget, we can’t have art on every page of the book.” So we pulled out all the sidebars and I joked this was my Silmarillion — the GRRM-arillion — and we would publish it later. So The World of Ice and Fire was published close to its original conception…and Fire and Blood is the first time I’ve been able to present the material as it was originally written. Plus, I wrote additional material for it.

_{^{George R.R. Martin gets candid about new book: 'What excites me most is I finished it'}}

etc

Certainly Martin is aware of Tolkien's Silmarillion (in terms of both content and concept) and references it multiple times in interviews, along with other of Tolkien's works, including his essays. I think it's fair to say that if he's not read it cover-to-cover then he's at least skimmed it.

Tolkien gave us all these histories all these appendices and genealogies and everything was was routed and it seemed as real as England or France or Germany when you when you read these things and since then that's become the style for epic fantasy. I see a lot of fantasy readers now expect they expect a fully real 'secondary world' as Tolkien called it and so certainly that's what I set out to creating in Westeros. Now some of this is a magician's trick [but] it really wasn't with Tolkien. You have to consider that Tolkien is, was a very unusual writer, I mean he was a linguist and a philosopher, spoke Old Norse and Old English, he was fascinated by myth you know he, the story was almost secondary to Tolkien. He spent years creating his Silmarillion and never published in his lifetime and the Lord of the Rings and The Hobbit were like the stories set in the world he created, but for him the world creation and the creation of languages was almost primary. If you look at it like an iceberg he, you know, they say that three-quarters of iceberg is hidden below thoughts below the surface that was certainly true [in his case]

And

My editors said, “This is going to ruin the entire concept of the book, we already spent the entire art budget, we can’t have art on every page of the book.” So we pulled out all the sidebars and I joked this was my Silmarillion — the GRRM-arillion — and we would publish it later. So The World of Ice and Fire was published close to its original conception…and Fire and Blood is the first time I’ve been able to present the material as it was originally written. Plus, I wrote additional material for it.

_{^{George R.R. Martin gets candid about new book: 'What excites me most is I finished it'}}

etc