How to view the number of subscribers to a public calendar I created on iCal?

Hello Dabaw,

Welcome to Apple Support Communities. 

Is this a public calendar that you set up? If so, On iOS, open Calendar. Tap Calendars > encircled “i”

Calendar subscriptions such as U.S. Holidays, for example, you are unable to see the number of people subscribed. Please feel free to leave feedback here: Feedback - Calendar - Apple

Here’s additional information on calendar subscriptions: Use iCloud calendar subscriptions - Apple Support

Let us know if you have further questions.

Take care.

Dabaw,

We appreciate you testing that. You can leave feedback about this here: Feedback - Calendar - Apple

That's the best way to have your voice heard about the functions and features that mean the most to you.

Take care.