"It is hard to argue that Eliot has made the same impact."
I would--but in a different way.
As I said, Orwell impacted political thought and introduced those terms and ideas...
But as I also said, Eliot's poetry completely redefined poetry, and I'd still argue that we've yet to fully "move on" from Eliot...Ginsberg and Plath are probably the best arguments for later poets having done so, but even in them you can see roots leading back to Eliot's style of poetry.
So Orwell impacted public thought, but Eliot reshaped the whole of poetry in the English-language.
What's more, if we talk about how "big" each were in their own time/after their time, as we did with Shakespeare/Vergil--
Orwell's been big, but Eliot both won a Nobel Prize for his works and has essentially held the title of de facto English poet of the 20th century. No one could argue Orwell was the de facto English novelist of the 20th century...not with so many other great talents making just as big a splash, and sometimes bigger (if we cross the Pond, I'd argue Hemingway's had a further-reaching literary impact than Orwell, and he, too, received top honors.)