Just going off the public numbers for one of google's ASNs[0], with the amount of public peers they have (and likely far more private peers, and I'm just assuming google doesn't buy transit and ignoring that), it's unlikely that a DDoS would ever cause an outage for more than a small subset of people. You may be able to saturate a link or two, but that's not difficult to route around generally.
That is of course only for network saturation DDoS, I'm sure there are ways google could be ddosed at the application or server level, but they likely have enough infra in place to be able to eat the attack without anyone outside of google noticing.
Comments
Just going off the public numbers for one of google's ASNs[0], with the amount of public peers they have (and likely far more private peers, and I'm just assuming google doesn't buy transit and ignoring that), it's unlikely that a DDoS would ever cause an outage for more than a small subset of people. You may be able to saturate a link or two, but that's not difficult to route around generally.
That is of course only for network saturation DDoS, I'm sure there are ways google could be ddosed at the application or server level, but they likely have enough infra in place to be able to eat the attack without anyone outside of google noticing.
[0] https://www.peeringdb.com/net/433