If we assume that each CSR can handle an average number of cases then the absolute number of cases handled by a human increase with even 1 CSR taken on. The Mythical Man Month doesn't apply as there's no time limit on it.
So no, I don't need to answer that beyond any number greater than there are now, which I already did.
Average wage in the US is ~$50,000 per year - without holidays I might add - and their total workforce was ~120,000 strong as of 2018. If someone claims that Google increase its workforce 6-fold by only hiring CSRs and not make a significant difference in customer satisfaction then what can be said?
Or let's make it 3-fold and claim the other hundred grand is for training and office space (yeah, can't get a CSR to work remotely and definitely can't earn less than minimum wage nor those jobs be abroad because I'm building an unrealistic quibble).
It's like people arguing that you can't know the sky is still blue on Earth because you haven't been outside yet today. Please. Worse than that, it again obscures the real questions - what level of CS does Google need to provide to stop customers going to a competitor, which is the level they have now, and hence, since they're too powerful to be competed with what should be done about it? What can be done about it?
So no, I don't need to answer that beyond any number greater than there are now, which I already did.