If you have enabled Payments in QuickBooks to allow your customers to pay online, please read the following.
Edit the invoice email template to include the payment link for Quickbooks.
Settings/ Email/ Invoice/ Edit
Generate the invoice in Datagate. Do not email it to the customer
Select the invoice(s) and “Mark as Sent”
Export the invoice to Quickbooks Online in the usual manner
Back in Datagate, select the invoice(s), “Email Selected”
When your customer receives their invoice via email, they will can click the link in the email to pay their invoice via credit card.