But another to not know the definitions of words you are using when you should know that? Can you say "I have a million dollars in the bank" when you honestly believe "a million" = 1000?
IANAL and I have no knowledge of the business/financial/contract end of things. I do know I've signed quite a few "due diligence" and "reasonable effort" clauses. I don't know how legally defensible they are in situations like user reporting when it's not specified.
In both categories of law, there is a subset of offenses that fall under "strict liability" — for which you can be punished regardless of your state of mind when committing the offense.
Fraud, like most criminal offenses, requires establishment of mens rea (knowing wrongdoing), so Sam is incorrect in saying that financial misstates are "felonies" on their face. But once you've become an investor you can bring a claim of breach of fiduciary duty (a tort) — rather than establishing that the CEO intentionally misled you, in this case you only need to show that they breached a "duty of care" — essentially, "you should have known".
How those responsibilities translate over to criminal / civil law would be a question for a lawyer. I think Sam's use of "felony" might be meant to get people's attention. Even finding yourself in an argument with your investors over civil liabilities probably means you have huge reputational issues that could kill you among the investor community.
Unless you specifically state that you are using the GAAP term "revenue", revenue could mean anything, just like "made" could mean anything, like saying "we made $1M last month".
I highly doubt if you were making a presentation and you said "We had 1M in revenue last month", and it wasn't actually GAAP revenue, I find it hard to believe you would be subject to lawsuit or arrest. In fact, arrest is even more of an over-exaggeration.
Even Groupon had a hard time defining exactly what its "revenues" were pre-IPO, and yet no one got sued or went to jail.
That said, why not use appropriate GAAP values? You should already know them, assuming you're keeping proper books, so it should be the easiest value to give.
"Revenue" can mean anything. Look up the term online, for example http://dictionary.reference.com/browse/revenue, and you'll see 6 different definitions. One of them is: "an amount of money regularly coming in". How is this definition of revenue wrong, or how could it result you getting sued? The answer is you won't.
Sure it could cause misunderstanding, but that happens all the time. As long as you don't misrepresent it as "GAAP revenue", you're perfectly fine using it in any reasonable way. Unlike what Sam Altman says, it's not a felony. My wife is a CPA and she laughed out loud when she read that.