Hello there, Ginfinch2611. QuickBooks does not currently send an automated email to you when a customer accepts an estimate; only the customer receives the confirmation email.
However, you can verify the status of an estimate directly within your QuickBooks Online account by going to the All Apps menu > Sales & Get Paid > Sales Transaction. Then, locate the estimate and check the Status column. If an estimate is marked as "Accepted," it means your customer has approved it.