You would need to look at a recent statement of the life insurance policy to find out what the cash value is, and most companies will allow a policyholder to borrow around 80% of that cash value. You cannot borrow against the face amount of the life insurance policy.
If it is a term life insurance policy or a newer permanent life insurance policy there will be no cash value from which to borrow against. Here's how you can learn more about permanent life insurance.