Always get a share of the revenue. Example: Forest Gump author got zilch because his share was based on profit and not revenue
And a share of gross revenue, at that. I'm sure all these definitions are written in the studio's favour. Apparently, Stan Lee never got anything for his creations either (and Spiderman grossed $800M+).
Stan Lee's famous for ripping off the creators of characters in comics he published, so I wouldn't feel too sorry for him.
'off the top' means revenues, not profits. Profit sharing opens you up to all kinds of creative accounting reducing the profits (or even turning them into a loss) to the point where you're not getting anything.
That's why they say: "profit points are for suckers".