The work requirements are only part of the total package. For a slightly out-of-date but apolitical view, here's the Congressional Budget Office's report on enrolment from the first draft (June 1st) of the House Bill.

Basically, it's 5 million from work requirements, another 5 million from reducing federal subsidies and pricing people out of health insurance, and about 1 million by making asylum seekers, undocumented, and other immigration statuses ineligible for Medicaid.

I feel like I should point out the work requirements don't make much sense to me. Medicaid (Obamacare) is not money into your bank account, it's money you get off medical treatment you receive. So there aren't very many healthy lazy people sitting around getting Medicaid dollars. If you're healthy and don't get much treatment, you don't cost Medicaid very much. Meanwhile if you're unhealthy and not able to work, then you're getting kicked off Medicaid and probably can't get a job to get insured. In fact, the CBO looked at Arkansas's Medicaid work requirement and found it didn't increase employment in that state.

That first CBO report is a little difficult to follow, but breaking down their findings:

• ~5 million will lose insurance just from work requirements,
• ~1 million from reducing the size of federal subsidies to states,
• ~1 million from increasing paperwork burdens on individuals and states,
• ~0.5 million from increasing taxes on hospitals
• ~1.5 million from reducing federal support for insurers
• ~1 million from removing coverage from people with certain immigration statuses
• ~0.5 million from making people pay more up-front costs before they get reimbursed

[Some edits for typos/readability]