Here's a bold statement: If it were proved that Weisel was 100% a liar and a fraud...the holocaust would still be a historical fact. What the denires want to believe is that individual witnesses somehow make the case for the holocaust, discredit a witness (which they've not done in Weisel's case, BTW) the house of cards as it were, falls. But the house of bricks that is the holocaust is built not on individual witnesses -- compelling, horrifying and edifying as individual witness stories are -- it is built on actions, laws, documents, photographs, film, etc. as well as individual witness statments. Indeed, like Himmler's Posnan speech, the best evidence is often that supplied by the perpetrators, not the victems.
In short, Wiesel -- though a powerful witness voice -- is ultimately irrelevant to the reality of Hitler's final solution. It is Hitler, Goebles, Himmler, Hydrich, Eichman and all of the little Hoesse's of the world that are the proof of the holocaust. In short, to prove the holocaust didn't happen you would essentially have to prove that Hitler didn't exist and that Nazism didn't rule Germany from 1932 till 1945. Prove Hitler didn't exist, you will easilly prove the holocaust a hoax. Prove Weisel wasn't an inmate at Auschwitz, all you prove is that Weisel is a liar and wasn't at Auschwitz...it proves nothing more about the existence and function of Auschwitz.