I’m sure he’s earned some money, just not the millions you had suggested.
As you noted, he was the #1 ranked writer here in 2016. Partner Program started in 2017. And when it started he didn’t immediately monetize because he was more interested in email addresses.
I’ve been in his annual coaching program for several years and he’s talked about it in the past.
Medium was always a vehicle to get him to where he wanted to be, which was a professional writer. But he couldn’t get a book deal without an email list. So he wrote here, built his list, and landed a massive book deal with a major publisher.
After he got what he wanted he moved on to other things.
Now his stuff is behind the paywall and he makes passive income. I’m sure it’s nice, but I don’t imagine it’s very much given that the bulk of his views are all pretty old.
But to your point, just republish something every 6 months to make sure the checks keep coming. ;-) No reason to leave any money on the table now that he’s gone.