Facebook does not actively promote Holocaust denial, rather it does not delete such content but significantly reduce the distribution of that content.
Facebook collects exceptionally detailed information about how users interact with everything on the social network and tailor itself to each user based on that information. So if someone searches or likes content related to holocaust denial, it would further suggest similar content to them.
Responding to this, Facebook CEO Mark Zuckerberg said they have a responsibility to curb fake news and misinformation, but maintained that Facebook should not ban publishers for spreading false claims, a position he described as 'too extreme.' In an email to Recode Decode, Mark said even though he finds the Holocaust denial offensive, he cannot stop anyone from speaking about or believing in the theory. If fact-checkers find a post to be false, it will lose the vast majority of its distribution in News Feed. And if the post crossed the line into advocating violence or hate, it will be removed.
According to CNN, the head of Facebook's News Feed, John Hegeman, said that Facebook does not take down false news. Facebook believes in reducing the distribution of misinformation -rather than removing it outright. Hegeman clarified that Facebook was created to be a place where different people can have a voice. And various publishers have very different points of view. Removing content would be going against their policy.
In countries where it is illegal, such as Germany, France, and Poland, holocaust denial content is not allowed as per the law.
Just because Facebook's policy does not restrict such pages, we cannot say that it is actively promoting Holocaust denial on its platform.