Assuming you have the paid subscription, there’s no explicit limit on how much traffic you can handle through Workers.
Obviously, Cloudflare doesn’t have infinite computers, so in theory with enough traffic you’d use up all our compute power. But, obviously, that’s rather difficult to do. And if you think you can – talk to us. We can deploy more machines pretty quickly if they are needed for a big paying customer. But very few customers are so big that they could overload us. In general, we deploy our machines ahead of demand, so there’s always capacity to spare.
Note that the total pool of available resources for your workers really is all of our edge machines. The only way for your particular worker to run out of resources is if we run out of resources for Workers in general. I honestly don’t know how much traffic you’d need to generate to exhaust our resources – and, of course, it depends on how much work your Worker is doing – but your requests per second would have to be at least in the 7-digit range.
@dmitry in your Twitter DM you asked about “surge limits”. Note that surge limits apply only to people that aren’t paying for workers (not even paying $5/mo). If you were actually thinking about the anti-abuse limits, see my answer here: Workers and sub-requests