One will never earn passive income on Medium. It's formula is that of a newsheet or a weekly or monthly magazine.
It works in a different way to what it used to work, and I, for one, am greatful for that. Yes, I do write about 5 articles a week, but I happen to be a compulsive writer, so it's more difficult for me to stop writing than to find something to write about.
After building up a readership, readers will often read through your past articles, and all of that earns. Also, when you link to the various sites that enable artists to obtain patronage, it becomes a good source of income.
I don't plan to be on Medium forever. I am, however, leveraging the platform, to be able to write a web series eventually. When people on Patreon earn $25,000 a month for what they produce, I want to be there.