Where this poll and the Watchtower’s statistic intersect is impossible to say. Watchtower counts active JWs only. The Pew Poll will likely be these as well as those who identify as JWs in whatever way, inactive, even DFed, former unbaptized publishers, Bible Studies, raised in a JW household but never really made any sort of commitment. If counted, I suspect the number would likely be double than merely counting active JWs, as reflected by Memorial attendance.
Those who leave the JW identification (as reflected in the Pew poll) would likely come more from the nebulous group, than those active. However, to some degree, I’m sure the same proportion of dropouts are reflected in the active count as well.
There were 136167 more active publishers in 2014 than in 2007. Most of these were likely Spanish speaking.