According to our very scientific calculations, Gendry (Joe Dempsie) will appear in Sunday night's episode of Game of Thrones. That is to say, the folks at Marie Claire spotted Dempsie's name on the IMDb page for episode five "Eastwatch," which seems to indicate that Gendry will make his triumphant return.
We've known for a while that Dempsie would appear on this season. In July, the actor walked the red carpet at the season seven premiere, which said a lot about his participation in the series. Gendry hasn't been seen in Westeros since the third season finale, when Ser Davos (Liam Cunningham) freed Gendry from Melisandre (Carice van Houten). For three years, he hasn't appeared on the red carpet. (In fact, a search on YouTube for his name with "Game of Thrones" reveals content from 4 years ago and content from three weeks ago — nothing in between.)
So, the only question was when he'd return this season, and it looks like the answer is this Sunday. Note: The IMDb pages for the first three episodes of Game of Thrones do not feature Dempsie's name. IMDb can be suspect, as it's user-edited and oftentimes poorly maintained, but the Game of Thrones-related pages are impeccable. There are a lot of characters to keep track of on this show, and the internet is very good at keeping all the files in order. See evidence of his once-upon name below.
Alas, the name has since been deleted from the movie database page, which could mean one of two things: Either Gendry is, in fact, in "Eastwatch," and someone removed the name in the interest of protecting spoilers, or the name was just a fluke, and he won't appear.
As Gendry is a crucial character in the show — he's one of the last known bastards of Robert Baratheon — we hope it's the latter.