I'm not sure what you are asking: if the box 5 is what the employer paid and box 1 is the actual tuition paid by the employee, your client, then you would enter it as you would any other 1098-T.

Box 5 is for money paid by others, scholarships, grants, employers etc., your clients payments are in box 1

If your question is, should your client receive the credit because the grade received was not high enough for the employer to reimburse the tuition, the grade is irrelevant to the credit eligibility.

As long as the other requirements on the Student worksheet are met, the client should be eligible for an Education credit. There is no question about passing or failing for eligibility purposes and plenty of parents and individuals receive ED credits, even though the person dropped out after the 1st semester.

I guess you could say you can get the credit for trying, not succeeding, as long as all the other requirements are met and your client actually paid the amount in box 1.