At least one source I found says the average salary of Twitter employees is $97k. (US only total compensation is closer to $300k with an average of $270k. But a lot of that is probably stock options which now must be paid in cash).
So I would imagine the total savings are closer to $250m compared to when Twitter was public but maybe a lot more in savings vs what Twitter would have bled considering the stock options portion of the compensation would have had to have been cash.