I can say the total submitted is over 26,000, but with what I have access to the only way to know an exact count of questions not eliminated is to count them all individually.
Before we were given the ability to look up questions in the database, it may have been possible to have a duplicate of an eliminated question rejected. There were also a lot more duplicates let in. The old way relied on our memory and notes of questions we came across. Now, we can see a question like the Upper Volta one and say that "sounds familiar." Do a quick search to see if anything comes up. When it does we can read the question and answers to see if it is the same. Also, we can see the percentage of correct replies. If it was a rejected question, it will be marked. I can't say how other evaluators decide on resubmitted dropped questions. Personally, if it still meets the criteria for the game, I will accept a new one.
I hope that helps clarify things for you.
I haven't gotten the ship captain question, so I'll be watching for it now when I go hunting.