National Security Innovation Pathway Act This bill authorizes the Department of Homeland Security (DHS) to provide special immigrant status to a qualified alien involved with research critical to U.S. national security. Generally, a qualified alien is one who (1) is employed by a U.S. employer to work and protect the National Security Innovation Base, (2) is engaged in Department of Defense-funded research at a U.S. institution of higher education, or (3) possesses scientific or technical expertise that will advance the development of certain technologies critical to national security. In addition, the Department of Defense (DOD) must confirm to DHS that the alien's admission is essential to developing critical technologies or otherwise serves national security interests. The spouse and children of a qualified alien may also be admitted. (The National Security Innovation Base is a network of persons and organizations engaged in research and production of technologies that support U.S. national security.) DHS may admit up to 100 principal aliens for FY2021 as special immigrants under this bill. This number shall gradually increase until FY2025. For FY2025 and each subsequent fiscal year, DHS may admit 500 principal aliens. Aliens admitted under this bill shall not count against various annual numerical limits. The Government Accountability Office shall report to Congress on an evaluation of the program by October 1, 2025.