These lyrics are (to me) as much like Robert Johnson's as a piece of salt-water taffy is like a praline. Both are sweet. Both are good. Both were contrived by someone who knew the medium. But they are very different. I think that you or I could easily concoct lyrics that have the same level of similarity to R. J.'s style.

I guess what I am saying is that, no, I don't think these lyrics are directly derivative. I could be wrong, though.