Pakistan was all out for 81 in its second innings in 34.4 overs, unable to cope with the pace of Gabriel, who finished with match figures of 9-92.
Pakistan's collapse was sudden but not surprising. It went to lunch at 35-5 then quickly dropped to 36-7.
Sarfraz Ahmed was the final man out in the afternoon session, top scorer on 23 in a familiar second-innings collapse by the tourists.
Earlier, West Indies lost its 10th wicket in the morning after only five balls to be all out for 268, a lead of 187. Legspinner Yasir Shah finished with 7-94, his 10th test five- for.
The deciding third test starts on Wednesday. Pakistan is seeking its first test-series win in the Caribbean.