I have a CSV file that I imported into Google Earth Pro. G.E.P. took the long/lat and placed markers where they should be, and when I select the marker the rest of the data displays in a box. Is there a way to link the two so that when the csv data is changed the data that shows up in Google Earth automatically changes as well?
When you imported your CSV into Google Earth, it converted it to KML for you, and that KML is what you see on the map. As you've seen, that's a one-time import/conversion, and if you update the CSV, you would need to import to KML again, in order to see the updates in Earth.
Unfortunately there's not a quick & simple solution to do what you want, where updates to CSV show up in Earth. What you would need to do is set up a system (other than Google Earth) that converts your CSV to KML whenever there's an update (or on some regular schedule). The resulting KML would need to be hosted on a server somewhere (or on your hardrive for local use only). Then you could create a NetworkLink in Google Earth that could load that KML. You can set up a NetworkLink to auto-refresh in different ways, like whenever the user stops moving the map, or on a time schedule, etc. The process of setting up a system to generate your KML and host it is complex, and depends heavily on what skills, tools and infrastructure you have available, and how you want to make the results available to your end users.