Paid Family Leave Pilot Extension Act of 2018 This bill amends the Internal Revenue Code to extend through 2022 the tax credit for employers who provide employees with paid family and medical leave. The bill also requires the Government Accountability Office to: (1) examine the effectiveness of the tax credit for paid family and medical leave, (2) recommend ways to modify or enhance the tax credit to further promote access to paid family and medical leave for qualifying employees, and (3) suggest alternative policies that federal and state governments could implement to increase access to paid family and medical leave.