I assume you know what profit is? He has expenditures (the money spent "answering questions") which partially offset his gross income.
by a long shot - definition of by a long shot by the Free Online Dictionary, Thesaurus and Encyclopedia.
The rest is an idiom. A "long shot" is a bet with very slim chances of winning. The meaning here is that if you would bet that all of his winnings are pure profit, it would be a very long shot bet that you would lose. You would not be even close to being correct.