“Get it all on record now – get the films – get the witnesses – because somewhere down the track of history some bastard will get up and say that this never happened.”

This is the supposed quote that so very many people evoke in claiming that Eisenhower predicted Holocaust denial. This is also, you may notice, sketchy as hell. Typically, when a quote seems to predict something that happened just as the quote said, it's a fake quote. In fact, there is no evidence of this direct quote. It is cited in no books. The first reference to it I could find was a blog post from 2007, and cited Wikipedia which in turn cited an article from the Dominican Republic (which also claimed that the UK no longer taught about The Holocaust.) Even that article states that he only said words to that effect; admitting it's a paraphrase.

Is it true that Eisenhower wanted to make the Holocaust undeniable? Yes. But it wasn't because he predicted a conspiracy theory decades later. According to a trustworthy source (Dear General: Eisenhower's Wartime Letters to Marshall), Eisenhower visited the camps firsthand so that he could provide a firsthand account to anyone who chalked up the horrors of the Holocaust to propaganda. That is not even close to what people online claim. Here's the actual quote:

"The visual evidence and the verbal testimony of starvation, cruelty and bestiality were so overpowering as to leave me a bit sick. In one room, where they [there] were piled up twenty or thirty naked men, killed by starvation, George Patton would not even enter. He said that he would get sick if he did so. I made the visit [to Gotha] deliberately, in order to be in a position to give first-hand evidence of these things if ever, in the future, there develops a tendency to charge these allegations merely to “propaganda.”

Not as soundbite-ready, is it? Beyond the poached paraphrasing, people seem to misunderstand who Eisenhower was expecting to deny the Holocaust. When people cite this as a fact today, they seem to be implying that Eisenhower was expecting anti-semites in the future to deny the existence of the Holocaust, and that's the reason for the documentation. In fact, though, the footage taken by the Army Signal Corps was used at the Nuremberg Trials to indict the Nazis of war crimes.

TL;DR Eisenhower was expecting the Nazis to deny the Holocaust, not antisemitic conspiracy theorists.