Maybe, I do not know how the number of neurons in a child's brain and the connections compare to Claude and its training but I would think it is comparable. Also, while a child might sleep the brain does not just switch off, there is still stuff going on that adds to the child's development.

I am, here, not counting time for separate instances of Claude (so 10 instances running for a year is not 10 years). So, I think the 8yo is still older.

Full disclosure, I am not a neurologist or computer scientist (although I find both interesting). I would consider fair criticism of this fair and would even like to see what those in those fields would have to say.