From their most recent annual report, at https://info.arxiv.org/about/reports/2023_arXiv_annual_report.pdf https://info.arxiv.org/about/reports/2023_arXiv_annua

From their most recent annual report, at https://info.arxiv.org/about/reports/2023_arXiv_annual_report.pdf https://info.arxiv.org/about/reports/2023_arXiv_annual_repor... "In 2023, arXiv received a $5 million grant from the National Science Foundation (NSF Grant 2311521 | “Frameworks: arXiv as an accessible open access research platform”). Distributed over five years (performance conclusion: 2028) this grant’s goal is to create a more discoverable and accessible arXiv to advance scientific innovation." That's $1 million/year. Total revenue in 2023 was $2,690,592.