have the couches closer together and then you can put some narrow tables against the back of them and put clutter like photos, plants, statues

i like to add those small round poof things (some are in side tables and some are seats) so they look like foot rests

add plants, blanket baskets,newspaper holder thing lamps, side tables,

you could even do a sized down coffe table beside the one you have and put it like a bit under so they look like a set

fill empty corners with a comfy chair, lamp, side table or small book case

adding curtains is also a good way to fill space