Yes, the 1099-R is taxable, until you indicate you performed a rollover.
You can do this by revisiting the 1099-R section in TurboTax Online. After entering the data, you will come to a screen with the heading "Tell us if you moved the money through a rollover or conversion"
Select "I rolled over some or all of it to an IRA or other retirement account within the time limits (normally 60 days)"
Next screen will ask "Did you roll over all of this $8,000.00 (Box 1) to another retirement account?", select "Yes, I rolled over $xx to another traditional IRA or retirement account (or returned it to the same account."