First of all, it looks fine the way it is. Negative space is needed in a room--you don't have to cram stuff into every nook and corner. Secondly, the big question is what do you want to DO in the room? This is the most important question to answer before you start furnishing a room. Does the room fulfill its purpose? If not, what purpose do you need--a place for children playing/game table/reading nook? If it does fulfill its purpose, then you just need to rearrange the furniture that is there. I'd take down the mirror and move the ladder shelf a bit further down. I'd also remove that little triangle table as it doesn't seem to serve any purpose. Finally, as I am not a fan of over-scaled leather recliners, I might get a new upholstered chair and ottoman in place of the recliner.

Get rid of the big lumpy chair. Buy TWO appropriately sized/complementary area rugs to define the two spaces. Get rid of the shelf unit, corner doo dad junk and small shelf unit too. get rid of mirror and plant. Use a round table, four small scale upholstered chairs, and set up a game space/cocktail space.

The result will add some color, provide brownout relief, clutter relief, and give both spaces comfortable purpose.

Rug for the floor

Move the end table to the other side of the sofa

Give the coffee table a quarter turn

Add a simple floor lamp in the corner

Lower the framed pieces over the sofa

Removed some of the small fussy items you have attached to the walls.

Then perhaps these square tables are not OK for your room. Use a round drum table and mount swing arm lamps on each wall.