Every time Star Wars makes the news, some no-nothing comics fan comes up with this particular piece of nonsense--that George Lucas was influenced by or, sometimes, actually "stole" his concepts from Jack Kirby's work in the 1960s and early '70s. The latest version of this tripe is here.
George Lucas certainly was aware of Kirby's work to some extent...but I suspect he was far more familiar with the King's Golden-Age and '50s material than with Doctor Doom or Darkseid. (Lucas, after all, is in his early 60s and his peak comics-reading years would have been when he was somewhere between 9 and 15--putting them at roughly 1951 to 1957.)
Furthermore, since Lucas has clearly established his debt to the old movie serials and Japanese cinema, Darth Vader's costuming can be explained by both. The mask and cape motif was a frequent villain's gear in serials...particularly those dealing in the "red herring" plot, where the villian is a masked man who might be one of three or four seemingly harmless characters. And the particular style of Vader's mask and helmet have far more to do with Japanese armor than with anything either Doom or Darkseid ever wore.
Oh--and the heroic son who is the offspring of the great villain? If you think Kirby was the first to come up with that one, you need to get out a little more.