It depends....do they have an Endoscopy Center where you would be working to do cases or is it an office job? If it's an office job, 8 appointments an hour seems like a lot for the doctor...not necessarily for the nurse. (You'd probably be working for 2-3 doctors at a time.) You would probably bring the patient into the room for an assessment of vitals, med rec., and nursing history and then possibly follow-up with setting them up with testing dates or scope dates. Sometimes the office staff will do Remicade infusions, too.
There's a professional group called the Society for Gastrointestinal Nurse Association. Look that up online and prepare yourself for the interview. In order to sell yourself, you could tell your interviewer that you're planning on putting yourself through this certification, if you got the job, so that you would be better educated to help them serve their patients. There is a TON to learn about GI but you could learn it on the job with some outside resources.
If it's an Endo Center where you would actually be doing the scopes, you could learn that on the job, too. If it's got 2-3 rooms running, you may possibly do 8 cases an hour but there's no way one nurse would be responsible for that many. Working at an Endo Center is a great job! You'd become an expert on starting IV's. It's always better to get at least a good year in on a MedSurge floor but if this opportunity is knocking...you can make it work if you're willing to continue gaining knowledge on your own time outside of the job. The hours and the comfortable, easy-going environment make it worthwhile! Good luck! Let us know what happens.