I am still trying to figure out if there is a way for a customer to accept or decline my estimate, is there a way to do this?

Hello,

Not integrated in QBO no there isn't.  That is a great feature suggestion though.

I advise you to submit that by clicking the Gear icon and selecting Feedback.

Let e share some information on how estimates work in QuickBooks Online (QBO), lisa-purafog-com. 

Estimates are non-posting transactions in your account. This allows you to send information to your customer to give them an idea of what the product or service will cost them.

Once you send the estimates through email, the option to mark it as accepted or declined by your customer is unavailable. However, they can inform you about it and update the status in QBO to show it's been accepted, rejected, or closed.

Here's how: 

1. Go to Sales on the left side menu. 
2. Choose Customers.
3. Click the customer name.
4. Find the estimate.
5. Tick the Action drop-down and choose Update status.
6. Tap the Status drop-down and select Pending, Accepted, Closed, or Rejected. 
7. Press OK to save.

For more details about estimates, check out this article: Set up and use estimates.

I've got a link here that provides you more insights about managing your estimates: https://quickbooks.intuit.com/learn-support/en-us/sales-and-customers/estimates/08?product=QuickBook....

Fill me in if you need a hand with running customer reports or any QBO related. I'll appreciate the opportunity to help. You have a good one.

@lisa-purafog-com 

You may need a 3rd party app to do so. Once your client approved your Estimate, it will release your Invoice automatically.