If the robot is owned by an individual taxpayer paying personal income tax on the income, and if you ignore taxes other than income tax that levied on labor income, and if you ignore accounting tricks, etc., this is fairly obviously true from the way progressive tax rates work.

OTOH, it becomes less obviously true when you consider how the robots are likely to be owned in the real world, the full set of taxes on income in the real world, and the greater practical ability of the rich to avoid taxation in the current system.