What amount should I put in for 1098-T? 2021 1098-T has $14,500 in box-1. Employer has paid $9,945 pre-tax and this amount is not in my W2 box-1. Should I put 0 or diff?

Enter your 1098-T, exactly as received and follow the interview. You will be asked if you got employer assistance. Enter the amount of pre-tax assistance received ($9945).  TurboTax will treat the difference ($4555) as eligible for you to claim the tuition credit. 

Normally, an employer is only allowed to provide up to $5250  of tax free assistance.  But, it can be more if the education is considered job related.  I assume you employer has made that determination and that's why you're getting more than $5250. 

No, you can put the amount on your 1098-T.  Further in the interview, you will be asked about employer provided assistance.  

If you receive educational assistance benefits from your employer under an educational assistance program, you can exclude up to $5,250 of those benefits each year. This means your employer should not include the benefits with your wages, tips, and other compensation shown in box 1 of your Form W-2.