If that one firm takes in 10 million a year for 20 years that's .2 Billion going to one firm.

https://www.opensecrets.org/industries/indus.php?ind=e01

https://www.opensecrets.org/industries/indus.php?Ind=E04

You easily get to billions, even if you just look at one sector, or one country, or one target. Their PR budgets are about a Billion a year.

The claim was “billions of dollars spent in an effort to increase public ignorance”, not political lobbying.