Earlier quoted context omitted.
Cloud Functions isn't 1:1 IIRC, once a Function is booted it keeps serving more requests once warm.
No, the concurrency of GCF is always 1. If the latency of your code handling request is 1s, to handle 100 requests per second you'll need to have 100 instances running.
Link for reference: https://cloud.google.com/functions/docs/max-instances