Samantha, sorry to burst your bubble, but the author in question is lying.
There's no way he makes the amount of money he says he does on Medium. I've commented on his other articles asking for proof, and he's given evasive answers.
Don't be taken in. If you'd like to know how to actually and realistically make some money on Medium, I suggest reading Shannon Ashley. Not to self-promote, but I write a monthly report on my stats and earnings here as well. REAL stats and earnings, not made-up ones.
Wishing you all the best in your Medium journey.