The "40% don't know that 6 million Jews died" is technically accurate (page 2) but slightly misleading. They thought less than 2 million people died, which is still pretty crazy. The phrasing I provided was how I saw it in the new article(s) that pop up. And that's for the people who actually have heard of it. Apparently 22% have never heard of the Holocaust at all or aren't sure they have ever heard of it (also page 2). However, the 66% stat is straight off of page 4 and not misleading in the slightest.