The Indiana 529 tax credit says it's limited to $1000, but the IN state gov website says up to $1500. Is TurboTax incorrect?

If your tax credit for contributions to the Indiana 529 plan is being limited to $1000, then you may not have enough tax liability on your state return to be able to claim the full credit amount.  You can only claim up to your tax liability.

That being said, after digging deeper into this, the form used in TurboTax to claim the credit (Schedule IN-529) limits the credit to $1000 for any filing status except Married Filing Separate (which is limited to $500).  This limitation is applied on line 14.  

Looking at the Schedule IN-529 form provided on the Indiana Department of Revenue website, the same limitation is being applied.  So, the forms being used to calculate the credit do not agree with the FAQ that you provided in your question.  Until the Indiana Department of Revenue form is changed, TurboTax is correct because both versions of the form currently match.

For reference, here is a link to the Schedule IN-529 from the Indiana Department of Revenue website.