Are you talking about putting a dining table somewhere in there or just separating the space? I like how they have the furniture arranged, I’d put a slim sofa table behind the sofa to further define it, and also put some bar stools at the island.

We'd like to put an actual dining table in there somewhere - we're just looking for advice on where to put it. There are two bar stools at the island that cannot be seen behind the sofa.

The logical place to put it would be under the chandelier (after upgrading it severely.) There are charts all over the internet to help determine size and shape for a specific number of people. Google for those and then decide on shape. Tape it on the floor under the chandy with painter's tape to see which one works best in your space. Don't forget you need 38-42" of clearance all around the table for chair scoot and sit space. If you plan for a rug, it should be 38-42" larger than the table yet not run into other furniture. If you entertain larger groups only once or twice a year, you may prefer a drop leaf or extension style table for those occasions.

I agree with decoenthusiaste...the table should be located under the light fixture. However, your space does have some challenges, so I would caution against purchasing sectional. I fear it will bring you more pain than joy situating it in the room. A reasonably-sized sofa and a couple of chairs will be easier to place in the room.

Move the sofa to the window wall so you have room for the dining table under the chandelier

Move the TV to the wall shown above so there is plenty of room for all your tasks.

Consider turning your sofa ninety degrees to face the tv on the interior wall and use that side of your space for your living room and use the area adjacent to the exterior window wall as your dining space. Try centering your table under the chandelier.