The safe harbor protects sites whose users infringe copyright, if certain conditions are met. I don't think it applies to advertising.
An example of safe harbor protection would be something like a user uploading a copyrighted song without a site's knowledge. If the site did not know about it, did not benefit from it financially, and takes it down when they are told about it, safe harbor protections would probably apply.
In contrast, Facebook knows the content and targeting options of every ad that they publish, and makes money from the ads.
I believe you're thinking of OCILLA which is USC Section 512(c) [0].
You might want to look at USC Section 230 [1] which says "No provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider."
An example of safe harbor protection would be something like a user uploading a copyrighted song without a site's knowledge. If the site did not know about it, did not benefit from it financially, and takes it down when they are told about it, safe harbor protections would probably apply.
In contrast, Facebook knows the content and targeting options of every ad that they publish, and makes money from the ads.