The blue bar under the tax refund is half full, but my returns have been accepted by the irs for over a week... what does it mean if it stays halfway?

It is best to check the IRS website refund status also known as the WMR it gives you a better picture of what is going on as it is straight from IRS not TT

That blue bar will stay at the halfway point until your refund date shown on TurboTax is reached, whether you've received the refund or not.   This is simply because the IRS does not update TurboTax anymore after the return is accepted.  The information provided by Ajuarez79 is correct that Where's my Refund has the most accurate information.

Here is help for tracking your Federal REFUND:

https://ttlc.intuit.com/replies/3288568

Here's help for tracking a state refund if you are getting one:

https://ttlc.intuit.com/replies/3300211