The Debaltsevo pocket is almost closed now. Only a narrow strip of land connects the pocket to the remainder of Kiev territory. And it is impossible to move supplies through this strip, as it is under constant shelling by the militia.
Closing a pocket or crushing it are two different things. The Vyazma and Bryansk pockets or the Korsun-CherKassy pocket are all stylish examples for successful encirclements where the defenders managed to hold the line and finally broke out.