It also depends on what they write about because some topics are a lot more popular than others.
One common issue I see a lot of writers make is that they treat Medium like a journal, which is fine but they shouldn't expect people to read those type of posts.
Writers need to find a way to provide value, whether it's being helpful or entertaining.
Engagement is also another big factor. Way too many writers publish something and just leave. Or they might read three articles in a day.
Of course, it's possible to do everything right and still struggle because Medium doesn't make sense half of the time.