Here are some excellent comments on “Kirby the Liar vs. Lee the Liar” post from Facebook.

As far as I know there is no interview where Kirby said he did layouts for the Iron Man story. That bit of information came through Mark Evanier based on conversations with Don Heck, Stan Lee, Kirby, and others about the early years at Marvel. Evanier explains: http://www.povonline.com/jackfaq/JackFaq4.htm.
As you can see Kirby’s comments were not in an interview but came about because of conversations he was having with Mark. For all we know Evanier may have asked Kirby, “Jack this splash page looks kind of like your work…did you do any layouts on this?” In any event Evanier checked with Heck who at first confirmed Kirby had done layouts, and later recalled Kirby had not done layouts. And Evanier recounts similar confusion on the part of Bill Everett re. the first issue of Daredevil. BTW Don Heck told Kurt Busiek that in any instance where there is a Kirby cover introducing a new character the character had been created by Kirby. In any event the idea Kirby lied about doing layouts on the first Iron Man are a big ado about nothing. It’s clear the plot is based on Kirby’s (Dave Woods?) Green Arrow story, and that is probably the source of why both HECK and Kirby briefly said Kirby had supplied layouts. Yet today when this story is commented on people eager to attack Kirby try and present a picture where Kirby said he did layouts and Heck disputed that. But that is not what happened. Kirby said he did layouts, Heck confirmed that, and later Kirby and Heck agreed Kirby had not done layouts. Evanier: “The first Iron Man story was wholly drawn by Don Heck. The first Daredevil story was drawn mainly by Bill Everett. Steve Ditko and Sol Brodsky completed the inking, mostly by filling in backgrounds. Kirby aided Everett in some undetermined manner, though he definitely did not do full breakdowns as has been erroneously reported about this story and the first Iron Man.
These falsehoods, I had a hand in spreading back in the early seventies. At the time, Jack claimed to have laid out those stories and, I repeated his claim in print — though not before checking with Heck who said, in effect, “Oh, yeah. I remember that. Jack did the layouts.” We all later realized he was mistaken. Soon after, I met Everett and found him to be equally confused. He initially confirmed it and then, when I told him I didn’t think it looked like Kirby layouts, he said, “Oh, I guess it wasn’t.”
The confusion in these cases is, I think, understandable. Heck and Everett both did do work over Jack’s layouts…just not on those stories. Both also believed that Jack had contributed to the plots of those debut appearances — recollections that do not match those of Stan Lee.”