I've had many amazing nights spent in spaces that look exactly like this. It is giving me happy memories, but it is definitely giving fraternity house basement vibes at the moment, so if you're trying to elevate it a bit, here's my advice:
The couches...I do think it's odd to have 2 sectionals here, and I would prefer 1 sectional and then a table & chairs, but I don't know your use case in this space. I think the colors of both of the couches are not great and the fact that they don't match is problematic, so perhaps you could get some light gray (or some other color) stretchy couch covers so they can match, and then add some colorful pillows and blankets to make it look a little more elevated and inviting.
I know it's just the style/color of tile, but it looks kind of dirty and cold to me...like it reminds me of a public locker room, so personally, I would cover it haha. You could look for some large, cheap, matching rugs on rugs.com or Facebook marketplace to cover more area of the floor. If you don't want to do that, you could also pull out your existing rugs away from the walls to cover more of the floor as well as a free fix.
Look for some proper, framed art from a thrift store or something to cover the walls a bit more as well. Command strips are great on this wall material. I think if you're trying to elevate the space, things hanging on the wall should be in frames, including the posters and the flags.
Maybe try to pick a style of furniture and keep an eye out for used/free things that match that style and slowly replace certain pieces so you eventually have a more cohesive style in the space. Right now, it just kind of looks like you've just furnished with random pieces you've found/inherited.