I feel like an important step for a language is when people outside of the mainline language culture start using it in anger. In that respect, Zig has very much "made it."
That said, if I were to put on my cynical hat, I do wonder how much of that Anthropic money will be donated to the Zig Software Foundation itself. After all, throwing money at maintaining and promoting the language that powers a critical part of their infrastructure seems like a mutually beneficial arrangement.