I haven't seen the movie.
I can imagine a scene where they set up the cameras and stuff pointing at a hill. The portraying Hugh Glass get in costume and make up, and walks around the hill out of the area of the camera view.
When the director yells to start, the actor climbs up the other side of the hill and comes into view and then walks down the near side of the hill, leaving a trail of footprints behind him in the otherwise pure snow.
Or maybe they bring in a machine with a long extendable broom with a camera. They have the actor playing Hugh Grass walk away from the camera leaving tracks in the snow and they extend the broom with the camera after him so that the camera stays close to him but doesn't male tracks in the snow. And they can use a zoom lens on the camera to keep the actor in close view even if he gets hundreds of feet away from the camera. They just have to make sure that the angle with the sun doesn't make the camera and crew leave any shadows visible in the scene.
Or maybe the actor walks from right to left in the shot and the camera is at a distance from the actor, and all the crew stay out of the camera angle so they don't make any tracks visible within the image.
Or maybe they have an artificial snow-making machine and huge blowers, and they use the blowers to blow away most of the natural snow and then use the snow-makers and snow-blowers to spread artificial snow around to the desired depth. Then the actor walks through the snow as they film.
If the director wants to re-shoot the scene at the same spot, they blow away the artificial snow and lay down another coat of artificial snow to the correct depth, getting rid of all tracks in the snow, and re-film the actor walking through the snow and making tracks in otherwise pure snow.
And they can use this technique over and over again in the same place if necessary, to get a shot that the director thinks is good enough.
When ever a crew person is visible in a movie or TV show that is counted as a blooper. It is something that the crew of the production try to avoid. So the people in charge try to position all the crew members where they won't be on camera during the filming. And if the crew persons might leave footprints in real or artificial snow or mud or something, the director will try to make sure that the crew persons don't step anywhere that will be in the camera view during the filming.
Arranging the film crew so they can do their jobs without being on camera or leaving foot prints or showing their equipment or equipment shadows on camera is one of the requirement that filmmakers have to think about when planning how to shoot a scene.
So I don't know anything about filming The Revenant but those are my ideas about possible techniques used to avoid showing other footprints in the snow scenes.