Without datasheets for the specific items in question; I (obviously) can't come up with an actual worst-case-scenario air consumption figure; however just off of the top of my head:
The ATC spindle (if it's at all like the ones I'm familiar with the construction of) will only consume a significant amount of air during the tool-change operation; and compared to the other devices you mentioned, it's not very much.
The coolant system and the venturi vacuum pump are going to be the big air users. Exactly how much will depend on exactly which unit you get/make; and what it's settings are. I've seen mentions of consumption rates in the neighborhood of 4 to 5 CFM @ 90PSI; all the way down to less than 2 CFM.
The tool sensor, like the ATC spindle, will only use air while it's in operation; and depending on how you set it up, probably not that much.
With the air consumption of the coolant and venturi systems being the driving factor; I'm going to hazard a guess that you might be looking at a 220v compressor rated for continuous use... perhaps something like this:
https://www.californiaairtools.com/c...e/cat-15033cr/
It's not cheap, though... they want something in the neighborhood of $1500 for that one.
An idea that I just had - which means it may or may not be any good - is if you DIY the coolant system and venturi vacuum source; I'm wondering if they could be combined somehow? IIRC, the coolant system has a sort of venturi in it; for injecting the coolant fluid into the air stream; and the venturi vacuum source generates a stream of cold, high-velocity outgoing air - if you could just inject the fluid in the outgoing air of the vacuum ventiri; perhaps they could function on the same volume of compressed air from the compressor?