With the way that people can make fake screenshot and how Far Cry 5 is also being teased with a Wild West setting, I'm going to trust this screenshot as much as I trust Rayman being in Smash Bros.
https://www.youtube.com/watch?v=aY0Msvnv6WA
Kudos to the original creator BTW for making this look really convincing to start up his "Smashified" channel. The point though is that much like how Omni was able to make that look very convincing and fool everyone into thinking that this was real, it shows that with a bit of talent, we can't really tell if something is real or not. Even in this case where we have a guy leaning against a post, there is always that possibility where someone threw in a few things to make a "western setting" and shipped it out on the internet.
We'll see of course coming soon if this is indeed related to Far Cry, RDR or just something to trick people into thinking it was one or the other.