currently 150m worldwide
https://www.forbes.com/sites/scottmendelson/2020/09/07/box-office-movies-tenet-chris-nolan-150m-robert-pattinson-john-david-washington-dunkirk-interstellar-inception/#7ad1ec3b3885
Forbes dude thinks Tenet will end up 350-400m ww
I'd say about 250-300m more likely
Obviously had there been no Covid then it'd have been on for Interstellar/Inception BO