Lots! It made $363 million off a $200 million budget [1]. That's probably lower than the studio expected for such a big movie, but still a solid profit and especially good in today's post(?)-covid box office.
In other words, its pretty unlikely the theatrical run yielded a profit.
Also the $200 million production budget does not include promotion/advertising.
So it's very unlikely that Tenet made a profit at the box office, however there's streaming deals, physical media etc which can earn a pretty penny, particularly if something becomes a cult classic. Blade Runner and Starship Troopers were box office failures having has made lots of money afterwards.