Yeah.

He is reliably getting done in one single day what would take a normal developer 5 months of M-F work.

Also singlehandedly building a $1b business in a niche that he won't talk about...

By my definition 10x/100x dev means a person who makes decision which require 100x less resources to execute to achieve the same goal. For example, one can build clean, maintainable and monitored codebase/infra, which will support business goals and rapid evolution in long term, while some group of mediocre engineers can build overcomplicated system, over-polluted by bugs and technical debt, which will be significant liability rather than useful asset.

That's probably what it means but it's also a weird thing to measure because depending how you define "average" you can juke the stats any way you want. If I said "hire" to a random resume that comes in for a job, the value of either the median or mean developer is likely very close to zero if not negative, and that's probably true even if you just look at devs who are actually employed writing code for generic companies. If you restrict to better companies you quickly climb the productivity curve, and at places like Google it's pretty rare to find someone who is a 10x dev as compared to company peers (though you can have 10 or 100x impact pretty easily if you're good at almost any part of business other than writing code and know how to thrive in a bloated corporate environment).

Yes, I would rate my development productivity to be roughly 100x of an average developer.