There's a big difference between who claims to be a JW and who is actually a JW.
- JW Periphery: There are those that claim they are JW to a third party researcher: estimated to be ~14M people worldwide, this could be people that were raised, have been baptized or are studying, those that sometimes still attend, those that only attend for the memorial or those that still believe but don't attend etc etc they never really took up another religion, so they're often still counted among the JW by a third party.
- JW Adherents: There are those that the WTBTS claim to be a JW: estimated to be ~7M people worldwide, these are all the people that have been baptized and are regularly doing whatever qualifies them to be counted. These include PIMO, some apostates, some that go through the motions, those that do the minimum in public but in private don't really do anything, those that repeatedly get disfellowshipped for smoking or adultery and then get reinstated a few months later.
- Sheep: There are those that conform to all of it, both in public and in private, but don't really do 'more' than meet the requirements. They are children and family of elders and pioneers, those that have some form of appointment and have to keep up appearances or want the social interaction. They may not believe all of it but they would never say so out loud. I think that's about 2M people, it's really hard to quantify as you have to be "inside", but I would say that accounts for ~30% of any congregation I've ever been in. If the really hard times come, or the "core" falls out of their social fabric (for whatever reason - death, disfellowshipping etc), they quickly spin out to the JW periphery described above and within a few years or a generation they disappear completely.
- Goats: There are those that are hardcore JW's for life. They are pioneers and elders that truly believe. I think based on my personal experience, we're talking less than 500K-1M worldwide and dwindling faster than any of the above groups. They are the ones having part time jobs and giving everything to the WTBTS, they are hard on everyone around them to the point of sociopathy. When they wake up, they crash quickly out of the organization.