You cannot use the deadline in the Survey schedule as it is an absolute value

If the Deadline days property has a value greater than zero, the survey's deadline will be set from the day the survey is launched, plus the specified number of days.

If the Deadline days property contains a value, the Survey schedule object will not utilize the fixed deadline specified.

When creating a new Survey schedule object, you will no longer see the fixed Deadline field. Instead, you will only have the new Deadline days field.

When editing an existing Survey schedule object, the Deadline field will only be visible if it has a value.

INC-266043