I don't know how things work in China. In a country with an actual legal system, you have to prove actual damages.
Given the type of concern here you actually just have to make a case that the other side has been rewarded by their illegal use. Which is very clear when you look at sales numbers. That's where the sum is coming from.
That said, there's an issue of good faith with the deal with the parent company and frankly where's Proview's iPad. One could argue that if they aren't using the name themselves, or rather weren't before this whole thing started, then perhaps they shouldn't be able to claim rights to it. And I seem to recall at least one article that pointed out that there was no use before they realized that it was Apple behind the sale. Then suddenly something was released, triggering all of this.