My flight lands at 7pm meeting family at Rose and Crown for an 8:45 reservation !
I also think getting to R&C by 8:45 pm will be a challenge, but not impossible if everything goes your way.
I can't remember a time when we didn't get to the resort by 90 minutes after I walked off the plane. (I do not count the time it takes to get off the plane because some of those people getting off are very S L O.......W)! Try to get a seat near the front of the plane and only carry on what you would be able to take into EPCOT with you so you don't have to stop in the room or at Bell Services. Remember you will also have to go through bag search at the International Gateway, so small or no bags are best. Magical Express can take care of your luggage if you use it, but it may be quite late before you see your bags. If you have to wait for your own bags at baggage claim, there is no way you will make it to R&C before EPCOT closes at 9 (or 9:30 if you're going during the holiday season).
It will take about 15-20 minutes to walk over to the R&C from the BWV lobby (assuming you already have a ticket and do not have to stop at Guest Relations or a ticket booth. Unless a boat is just about to leave the BW dock, you will want to walk rather than wait, It will be much faster).
If you don't have to check in (maybe you are staying with someone else who will have already checked in and picked up your magic band?), you might just make it. If you have to check in, try to use online check in so you know your room and only have to drop off your carry on - either with Bell Services or your room. Check-ins can take 15 - 30 minutes or more, depending on how many are ahead of you and how many are working the desk.
Tell your family, you'll do your best and not to wait for you, but with a bit of luck, you'll be there before IllumiNations starts.
A taxi will cost in the neighborhood of $60-$75. IMO, that's too much just to make a dinner reservation, but if you must be there, that's the way to go.
Good luck!