You can read a 1997 interview with Eisner about Kirby from TJKC #16, and an early 1980s conversation between Kirby and Eisner is available in WILL EISNER'S SHOP TALK.
There is another thing I can tell you. I did a book called The Dreamer [Kitchen Sink, 1986], in which I showed Jack Kirby, and Jack said to somebody, "I didn't think Will liked me that much!" (laughter) He always called me "boss." (laughter) I said, "Jack, we're old men now, you don't have to call me boss anymore." "No," he said, "you're still my boss." (laughter)