I'm not sure if an accent wall will help in making the room appear lighter.

Some other ideas for you:
- lighter coloured throw cushions on the sofa to break up the large dark brown area
- just letting the curtains hang straight down on the sides of the windows, without the tie-backs will let more light into the room
- an area rug will bring some warmth to the room (the rug needs to be big enough to go under both front ends of he sofa)
- large pieces of art above the sofa

There's a start for you without the need of having to paint :-)

An area rug, new lamp (s)...a pic/art of some type above sofa would help the room. Are u considering new window treatments?

Ah yes, beautiful but tight and small looking. Possibly throw a wide mirror/art on wall behind couch, drop the drapes and ad wooden blinds to bring out the riches of the couch. and definately a rug with olive green and woodsy colors. That should really open that whole room UP, make is warm and add some cohesion!

I agree, the wall color isn't really issue here. Try updating the curtains, add area rug and some accent pillows.

YES, accent pillows!! good call.

Doing an accent wall is not going to lighten up the room.The best way to lighten up the room is add more lighting. Seriously. Get a larger updated lamp that will take one or two 100watt bulbs. Add a floor lamp.
Placing a large mirror in the room will bounce light, just be aware of what the mirror reflects, i.e. outside is great, a closet door not so great. Adding a light or bright colored area rug will help immensely to divide the brown sectional between the brown floor. The drapes tied back looks rather old fashioned. Either hang them straight pushed as far off the window as possible or consider replacing them with a more sheer billowy fabric.
After you get some light into the room, then add some colorful accents. Pop some Tangerine or Turquoise.
Or how about some Citron Yellow or Rasberry.

Hi there
1. Love the Olive walls
2. Love the gloss level of the leather.
3. Replace blue drapes with a lovely white/beige linen. Hang new rod/rail under cornice to lift height. make the rod/rail wider. This will allow the curtain when open to hang over the wall and not the window. Makes the window look much larger.
4. Get very large rug.
5. Change the coffee table. 2 round drums. The couch is so large, that you could move the 2 drums as required. A coffee table should be about the same height or one or two inches lower than the seat height of the sofa.
6. A long large quaint metallic framed mirror above the couch.

With love
Samantha xxx