Arguments for influence

Anselm Ruest: reviewed the Nietzsche controversy in his 1906 biography of Stirner and came to the conclusion "that Nietzsche had read Stirner, but withheld mention of him in his writings because he feared that while it was 'a positive philosophy which yearned for life', it was apt to be 'misused by many readers as a justification for petty crimes and cowardly misdeeds.'"
Paul Carus: Paul Carus wrote the following in 1914 about their relationship:
Gilles Deleuze: Gilles Deleuze suggests that Stirner was a critically important negative influence on Nietzsche. From this perspective Stirner's egoism was answered by Nietzsche's self-overcoming and "the theory of the higher man".