Do person gets a save? If they do can they escape with grapple check or escape artist?
Do person gets a save?
From the monster entry, "A target hit by a cube's melee or engulf attack must succeed on a DC 20 Fortitude save or be paralyzed for 3d6 rounds."
If they do can they escape with grapple check or escape artist?
As per rules, anyone engulfed "gain[s] the pinned condition," so they'd use the normal grapple rules to (fail to) get out, using either a grapple check or the escape artist skill.
Ah, yea, missed that line.
So since it says "until they are no longer pinned" means as soon as they are not pinned they get out?
That's my reading, yes.
Do they at any point enter any of the four squares the cube fills? If they do, are they expelled into the same square they came from? If not, what happens if the cube moves away from them?
Do they at any point enter any of the four squares the cube fills?
To engulf, a cube enters the square they are in.
We've usually ruled that the engulfed creature continues to be carried with the cube. If someone had ever escaped, I would have put her at the closest available space.