What are the odds this scene is real? Not very good, I'd say. The photo is from 1923. I found it in a book by Mark Sloan titled Hoaxes, Humbugs, and Spectacles. Despite that title, most of the photos in the book are not fake. The majority show circus performers and publicity stunts. Sloan titled this photo "High-Pressure Hijinks." He provides a short caption:
Perhaps this soldier needed a lift. Experimenting with water pressure outside his barracks, he discovered an ingenious alternative to mounted patrol.
(The New York Times; courtesy National Archives and Wide World Photos)
Pressure from a fire hose would be enough to lift a man straight up. Check out this youtube video of a car being lifted by water pressure. But I doubt a man would be strong enough to keep the hose pointed downward. The tendency would be for the hose to kick him straight back. I'm guessing the photo is a composite -- the soldier having been cut-and-pasted onto the background shot.