It depends who puts it in the store. The author still has all the rights to the software no matter if he puts it under GPL, but puttng it under GPL doesn't give anyone else the right to sell it in the app store.

Edit: Also, the app in question is under MIT and the used libraries under various permissive licences (https://github.com/mtigas/iOS-OnionBrowser/blob/master/LICEN...).