In order to really do the math here, you'd have to determine whether such drugs are as likely to be created under non-capitalist regimes. In other words, even if capitalism has less-than-ideal mechanisms for distributing lifesaving drugs widely (during their patent period at least), maybe it is better at creating lifesaving drugs in the first place. It's possible that the net result of the capitalist pharmaceutical industry is millions of lives saved. Without taking that account, you can't do a real cost-benefit analysis.

Of course, it's probably not really possible to do such a comparison, because there are so many other factors, and state intervention is everywhere even in capitalist countries, via publicly funded research.

I think the only really fair way to compare which system causes more deaths than the other is to look at overall health outcomes and lifespans.