On a 1997 Chevy Blazer, whether you have to drop the fuel tank to replace the fuel pump depends on the specific model and configuration. Some models allow access to the pump through an access panel in the bed of the truck (if it's an extended cab or SUV) or under the rear seat. Others require dropping the tank.
In short: It's highly likely, but not guaranteed. You should consult a repair manual specific to your 1997 Chevy Blazer (the engine and trim level matter) to determine the correct procedure. Checking online forums specific to your Blazer year and model might also give you some user experience information.
