Even if Stephen King was influenced by Wolfe I would have a hard time saying that any one influence shaped the Dark Tower universe - it is such a complete, internally consistent magnum opus that can be traced throughout every one of King's books. King has written in the new introductions to the books that the major influence are (of course) Robert Browning's "Childe Roland to the Dark Tower Came," Tolkien, and the movie trilogy "The Man With No Name."

You must have stopped after Wizards and Glass since the last three books came rather quickly (two published in the same year). He picked the series up again after he almost died in a car accident, realizing that he couldn't die without finishing the books - he actually wrote that into the series.