Hi @sadashay,
Welcome to QuickSight Community!
One option that comes to mind is to create a Lambda that is executed each time a file is created in that bucket, this Lambda would grab the file and write it to a standard named key, e.g. current_results. This would be the file you have mapped to your dataset in QuickSight. On this same Lambda you could also trigger the refresh of the dataset so you only update the dataset when you recieve a new file.
You can get some ideas on how to set up this solution in this tutorial, which is used to create thumbnails of images but you could modify to copy the file you recieved.
Off course there might be many other options to do this using different services but I think that for you case it is the simplest one.
Hope this helps!