If you read the article - it explains the advance vs. future revenue from book sales.
He had to have a block buster i.e. An Insider’s Bush basher book.
The article mentioned if it sells well then the author will make more money. Doesn’t say how much, which is besides the point, but the only guaranteed amount is 75k. With liberals alone buying this book it will probably sell well so maybe he gets a cetain percentage of sales like the editor does? What’s the breakdown?