I believe it’s possible for Google to collect demographic data without a Google account. From the below, they collect data from their doubleclick cookies (they own the data, might be Google accounts), Android device IDs (there’s a decent chance it’s a Google account still), or from an Apple ID (I don’t think this is linked to the Google Account).

They can probably make assumptions on demographics based on browsing history and interests that are pretty darn accurate with enough data (e.g. someone searching for all three of birth control medicine, a nail salon, and Victoria’s Secret has a pretty darn high chance of being a woman).

So no, don’t think it necessarily comes from Google accounts, but I’m sure they have a big contract to ensure Pornhub gets all the appropriate advertising revenue.

https://support.google.com/analytics/answer/2799357