If we kept the threshold for poverty at the same threshold it was 200 years ago, we'd probably say that capitalism reduces poverty. But as the standard of living moves upward, the threshold for poverty moves up too.
Poverty (in addition to staggering population increase) is a consequence of mercantilism and civilisation, thus recent technological advances in quality life that reduce poverty are bringing those people back to square one. It's hard to say if those technological advances would not have emerged under alternative economies.
Edit: Communist countries did have extensive well-functioning public health care systems (Cuba is an extant example) but that has to be balanced with the central planning in some larger communist states (namely China/Russia) that caused unprecedented famine and misery. Perhaps in an alternate timeline, if communist states weren't living in a world that was economically hostile (sanctions etc.) they might have thrived and focused on quality of life as a technology driver