Is it possible to have an expiration date or time on the form so the approvers would have limited amounts of time to process the form?

Also, is it possible to have an expiration date or time on the form so the approvers would have limited amounts of time to process the form?

It is possible to set expiration date on the form. Inside of this guide you can find how to limit submissions in the form: https://www.jotform.com/help/137-How-to-limit-submissions-in-a-form 

Please check Disable on date part of the guide I provided you. 

Hope this will help. Let us know if you need further assistance.

This disables the original form. I want to put a time limit once a form is submitted to the approver. So a student would fill out the form, put in the email address of their adviser, the form would go to the adviser and the adviser would have a limited time to approve/decline the form.

Yes, that is correct Disable on date will also disable original form. 

If you want to limit the amount of time for adviser you can add Global Countdown widget to your form. However this widget will be shown on the form both for your students and advisers. 

Inside of this guide you can find how to add widget to your from: 

https://www.jotform.com/help/252-How-to-Add-a-Widget-to-your-Form 

You can hide Global Countdown widget by injecting this CSS code to your form:

iframe[src*="countdown"] {

display : none;

}

How to Inject Custom CSS Codes

Hope this will help. Let us know if you need further assistance.