Altaic (Turkic, Mongolic and Tungusic, sometimes joined with Korean and Japonic in the broader Macro-Altaic proposal) is a disputed grouping most linguists reject as a genuine genetic family rather than the product of contact and chance resemblance. Tertiary sources report language counts for the proposal (about 66 to 74 living languages) but no combined speaker total, likely because giving one would imply endorsing the grouping as a real family.
What would resolve this Either broad scholarly acceptance of Altaic as a genetic family, which would make a combined total meaningful to publish, or a tertiary source willing to report a purely geographic or areal total across the proposed member languages without asserting genetic unity.
OpenHistorical and areal linguistics (Turkic, Mongolic, Tungusic studies)Wikipedia: Altaic Languages