I don't know if it's 10x, but there's definitely a huge acceleration in productivity. Attempts to deny that are basically just cope, or perhaps from people not using the tools correctly.
For new code, I treat it like a very knowledgeable mid level engineer who has a lot of patience to search the code base. We make changes a step at a time and I review them carefully and have it make changes I want. It's still a lot faster than doing it myself.