That's difficult. Symbolics alone had a billion dollar revenue in the 80s (sum of the years), with a maximum of 1000 employees. Then there were TI, Xerox, Franz, Lucid, LispWorks, Intellicorp, ... as companies. I'd guess that Lisp earned in direct sales around 2-3 billion dollars in the 80s... In a much smaller market. Inflation adjusted that would be 4-6 billion dollar today. A large Lisp company today might employ 20-40 people. Large user groups in companies might have less than hundred employees (like ITA/Google had (has?) a few years ago).