Honestly Eragon has more to do with King Arthur than it does with Tolkien.
I wasn't talking about plot. I was talking about style and writing quality (thus the language used).
Fortunately, Paolini's writing style is much better than that of most of the Arthurian writers, save perhaps Thomas Malory, Beroul, and Chretien de Troyes. He certainly beats out the anonymous monk who wrote "The Quest of the Holy Grail" and might edge out Spenser's "Faerie Queene" (at least he's more condensed and clearer than Spenser).
Although, Tolkien has more to do, plotwise, with King Arthur than even Eragon does, seeing as the Arthurian stories were one of Tolkien's influences (along with nearly every other medieval romance and epic).
But that's a topic for another thread.