Yes. The good CDNs are really fast. Individual connections may not hit 1Gbit all the time, as usually the bottleneck is the server with a 1Gbit NIC. The overall data speeds at the CDNs is pretty impressive. One I performed service in had 13GBit allocated just for the servers I worked on.

At a hotel in Palo Alto where I had 700mbit service, the CDN Steam uses was able to go at almost full speed.