Lol.

There are so many confounding variables and long-delay influences, it’s nearly impossible to compare.

Prior generation Chinese tended to eat much less than any generation Americans, which has a proven positive effect on longevity.

Older generation Chinese also tended to (might still?) smoke like chimneys, which has a proven negative effect on longevity.

Older generation Chinese also lived through some crazy ‘population bottleneck’ events like the Great Leap Forward, which can cause very odd one time and unpredictable long term effects on longevity.

China started and enforced their one child policy early on, which has very weird population distribution effects, which will also have weird influences on longevity for everyone (due to excess or lacking societal support, etc).

They have also (relatively recently) been exposed to a wide variety of industrial chemicals, artificial fertilizers and pollutants.

Americans have had rapidly shifting food sources, pervasive but changing exposure to pesticides and artificial fertilizers, a massive shift from rural to urban to sedentary knowledge work, and widely shifting stress factors across a wide variety of areas. And a rather unique ability to spend massive amounts of time in commutes and automobiles.

This is also offset in time; and quantitatively different than Chinese have experienced.