If you are able to center the tv cabinet along the wall, then move the seating arrangement away from it more, that will help, to begin with.
I suggest you look for two large and similar wall pieces for either side of it, and remove the items on the floor.

If you have the budget, two narrow matching furniture pieces, like demilunes, could fill in below.
Replacing the area rug w a larger one , extending underneath the sofa legs would also unify things a bit more (you have a lot of sofas!)

Even though I can't see the whole room, for some reason, I want to swap the brown leather for the red (kid's?) sofa. Remove the candle and the little table. Use a floor lamp in the right hand corner to balance the height of the poster on the left side of the TV.

Like Wendy's idea for balance and cost effectiveness.

I like the idea of a floor lamp [houzz=]

The first thing you need to do is add some height.
Like a matching pair of shelving units in a different material then your TV cabinet, metal or painted wood, etc.. Add some interesting books and artifacts, even a small lamp. Remove the art and little items on the floor.
I like what studio 10001 is suggesting as well.

We need a better picture of the whole space.

The picture I have on the left is a Fernando Botero print. Should I find another Botero print for the right? or another artist is fine too?