It seems that the best discussion of the question, Tom Shippey's, is mostly delegated to a footnote, with the article airily claiming that "Shippey basically agrees with Haymes's position". This is bizarre. Shippey is among the most respected Tolkien experts, while Haymes is apparently some guy people have googled at some point (but the links to his articles are now partially dead). Shippey is aware that "Tolkien may have overstated the lack of influence", but he is also aware that the parallels are not a case of Wagner-to-Tolkien influence but one of much deeper connections in  a century of philological study of the Eddaic stories accessible to both Tolkien and Wagner.