Need help to fill some Space Mid Century Modern Living Room  

Needs...
Honestly, no more sofas, couches it needs more color sorry but kind of bland. What about moving that chair and lamp away from the sliding door over to the right, move the couch a bit to the left. Maybe a rug for some texture and more color.

forgot to add...
also some greenery wouldn't hurt.

A Nice Rug or Pillows?
Adding some color with a modern rug would help complete the room. Linie Design's Ronaldo Rug is very chic and modern.

rug over carpet?
rug over carpet?

When I had a carpeted home,...
When I had a carpeted home, I used area rugs over carpet all the time. They help to delineate space and add color/decorative elements to a room.

yuck, pull the carpet up,...
yuck, pull the carpet up, put wood down

Don't know if it's just me, but...
I fail to see anything Mid-Century Modern about that living room!

It appears you have limited s...
It appears you have limited space but filled with bold furnishings. Personally, I would clear the room and start over again. If you must keep the lamp and sofa, then eliminate the blue dot on wheels. Replace with a side table next to sofa and perhaps a side chair with a low profile against the wall. Rectangular coffee table in place for the round table.

Yeah and....
The arco knock-off is o.k. of if you open things up. I'm down with ditching everything else and getting an open-frame sofa. The rug sounds nice too.