I was surprised to see this in the wiki of the Ring Cycle. From the number of correspondences between the two in how they handle the mythic material it seems pretty obvious he’s taking some influences from the Ring cycle but he claims absolutely not.
is Tolkien’s claim plausible?
Plausible? Sure - Tolkien almost certainly new far, far more about Old German/Norse mythology in general than Wagner ever did. Barring evidence to the contrary I’d be inclined to accept the general claim of common source material.
Not to say Tolkien may have been prevaricating a bit, though. Or at least I wouldn’t be all that shocked if evidence linking Tolkien in some way to Wagner were to turn up.
Yeah…common source material is most likely.
Tolkien almost certainly knew about Disney’s Snow White, too… 
Nah, I’m with Tolkien here. Coincidences all.
Deliberate borrowing- I doubt it. Subconscious influence- sure.
Wagner didn’t create the elements of the Ring Cycle himself - is Tolkien just not denying an influence by specifically Wagner’s version (the way someone might be influenced by fairy stories but disavow any influence by Disney versions)?
Nonsense. If I write a book that’s based on Germanic myth and YOU write a book thirty years later that is based on Germanic myth, they’re going to have some meaningful similarities even if you never read my book.
Common source material is a far more plausible explanation.
My sweet lord, just a coincidence.
The idea of a ring that makes you invisible but at the cost of changing your morality goes back at least as far as Plato.
Tolkien also claimed that he didn’t take what he wanted from Beowulf.
Sure – a Dragon’s ire is roused because a Thief comes in and steals a two-handled cup from his hoard. When the dragon wakes, he knows exactly what has been taken and comes out to vent his wrath on the nearest village. And Tolkien took NONE of this for The Hobbit? Sure.
Tolkien might not have borrowed from Wagner’s Ring Cycle directly, but there’s no doubt that he cribbed the features he wanted from the Germanic legends that lie at the heart of Wagner. Lots of analyses point out the similarities. (Have a look – if you can find a copy – at Lin Carter’s Tolkien: A Look Behind the Lord of the Rings, which came out circa 1970. But you can find more scholarly books and articles about it, too).
I could see Tolkien saying that he didn’t take from Wagner, because Wagner’s interpretation itself is shaped by Wagner’s goals, and differs from the version of the story I know from Bulfinch and elsewhere. If you want an interesting take on Wagner, read George Bernard Shaw’s The Perfect Wagnerite
It is not the ring that make’s folks invisible in Wagner’s ring, it is the tarnhelm.
The Perfect Wagnerite denies Gotterdammerung as the climax of the Ring cycle, and declares it merely high opera. Shaw is pushing is own philosophical ideas, and uses Wagner’s work to do so.
Wagner and Tolkien had the same or similar source material. I don’t believe that Tolkien cribbed Wagner. 
n.m.
This discussion looks at Lin Carter’s assertion that LoTR cribbed off of Wagner’s Ring, and picks it apart.
Verdict: Not guilty.
You’ll have to be more specific – that’s a long discussion, and most of it has nothing to do with Carter. In fact, some cites have Tolkien admitting to using material from the legends for some of his other works.
In any event, you’ll have to do better than that to show that Carter is wrong about Tolkien’s influences.
I got that, you know. Tolkien is so fine, after all.
I’ve read Christopher Tolkien’s “History of Middle Earth” books which goes through JRR’s edits of LOTR in great detail (sometimes too much detail). The changes to the story are IMO too organic to have been purposefully cribbed from another source. I think the worst charge that can be thrown at JRR is that he (like most authors) write about things that they know and he certainly knew German and Norse myth. Some of the other points seem weak. For example, how many stories have magic invisibility? Does that mean they all ripped off Wagner?
It’s just really hard to write a story that is wholly new that doesn’t borrow elements from some previous tale.
Did Tolkien “crib from” Germanic myth, or Beowulf, or was Lord of the Rings “based on” them? Absolutely not. Tolkien wrote his own stories, with his own elements and themes.
But was he inspired by them? It’s hard to see how he wouldn’t be: An artist draws at least some inspiration from everything he sees or reads.
We need a “like” button. 