Depends a bit on your table. Aim for 3 feet of clearance between all table sides and any wall or counter. I had a dining nook that was considerably tighter, and it worked. But I wouldn't design less than 30" clearance.
With the staircase and doorway, you have a really constrained dining area. You might consider builit-in bench seating along the window wall. That would give you more clearance from the stairway.
Q