The CDC estimates around 30 million symptomatic influenza infections in a year; in recent years, more[1].

And roughly three-quarter of infections are asymptomatic[2], so ~120 million total cases annually.

[1]: https://www.cdc.gov/flu/about/burden/past-seasons.html

[2]: https://www.sciencedirect.com/science/article/pii/S221326001...