But it doesn't tell the whole story. Could you survive on $2 per day? The implication of this claim is that you are not in "extreme poverty" at that threshold, but I'm not sure many people would agree.
The next natural step is to ask where the line really should be drawn? For many reasonable numbers, we can see that number has been rising in the past few decades. You can set your own inputs on the linked calculator based on where you believe the poverty line should be drawn and decide for yourself.
The confounding factor I see here is what do we call China? They've experienced an incredible increase in wealth under their communist system but is what they have really communism? It certainly has lots of attributes of both theoretical capitalism and western capitalism as practiced mixed in with communist concepts. Whatever it is, China, for better and worse, is a very different country than it had been because in part due their hybrid economic system.
The UK, a capitalist country, does.
Private industry is really, really good at innovation (e.g. discovering new drugs and treatments) and providing optional goods and services but most people just want a basic level of service and they want a funding structure that does not misalign incentives.
For example, optional basic health insurance doesn't work because poor people will quit the insurance program while they are healthy and then only unhealthy people will stay and bear the full cost. This raises the cost for poor unhealthy people and then they quit insurance and get denied access to care. Finally only the wealthiest people will have health insurance.
Capitalism is just a tool that's used to achieve certain outcomes. It just happens to work more often that it fails. Nothing more, nothing less. If a different tool works just as fine or better then it can be used selectively in areas where it's superior. Blind faith to any tool is stupid.
Communism on the other hand tends to fail by default and because it requires external forces to make it work, it breeds authoritarianism and then everything goes bad.
Western Europe vs Eastern Europe, N Korea vs S Korea, Colombia vs Venezuela, USA vs Russia - its pretty standard that the workers in the Capitalist countries have a better quality of life than those in the Communist ones.