We currently pass credit card data to the payment gateway via an import file. How is eAuthorize different, can it help us?

If you are currently exporting your transactions from your database in a file, uploading that specially formatted file to a payment processor, and then the processor is running the transactions, eAuthorize can help
The advantage of eAuthorize is that it will send the transaction straight from the database to the gateway, and eAuthorize will be able to receive an immediate response back from the payment gateway as to whether the charge was approved or not. So, it’s instantaneous and it allows the scripting in the database to check the result of the charge so different things can be done depending on the result of the charge request. These are things you can’t do when you’re batch processing them via an upload file.