Emerson was a favorite of Nietzsche's, though probably not such a major influence. Nietzsche would still have been Nietzsche if he hadn't read Emerson. But I've just finished a study of the Symbolists and it's actually possible to argue that an entire run of major French writers, from Baudelaire to Proust, would not have been the same without Poe. Bit of a stretch, but not impossible.
Not a stretch at all, in my opinion. Especially Baudelaire of course, where the debt is explicit and acknowledged.