You're not going to get more than 30 invitations/day unless the site policy changes.
As there are currently no "write" (send message, send invitation, sign up to match, ...) operations in the API I don't see knowing how many invitations are left is very useful, since to send any you have to use the website which tells you. If you think differently, perhaps you could explain, and provide a use case?
Ok but I really want the site policy to change from 30 to a number greater... Like 50 or something
Everything in the API is publicly available to all. Member invites is a function of club admins so would not fall within the spec of the API.
Well, here's not the place to ask for policy changes. Here we (the users of api.chess.com) are mainly asking/hoping and sometimes arguing to match the website's functionality. 
There are forums for help and support, and for feedback ... they'd be better places. Also of course the menu option "Make a Suggestion".
(I don't agree that 50 is better than 30 for a limit on invitations; we're more short of active players than we are of clubs, so far as my experience goes. But that's by the by; I don't much care, but this isn't the place to debate it. I mention my opinion so that you're forewarned that your proposal might not be universally welcomed.)
Thanks for the suggestion 🙂
Ok but I really want the site policy to change from 30 to a number greater... Like 50 or something
No offense to anyone is meant by this, but, generally speaking, I perceive "ideas" and requests like this to be from the type of people who like spamming others. (People who lack perspective, or don't care.)
For example, let's say the limit is 30, but you argue successfully for 50. Why 50? What's next, 75 or 100? Why so many? Why not just blitz all active users on a daily basis?
That's the way it comes across.
... Or something
I was hoping if we could have an option that could tell us how many people have been invited to a club by a person and we could invite more than 30 users per day?