You can send a reminder with automations with the Send reminder after step.
Add the reminder step after a Send message step. In the Send reminder after step settings you can define for how long the automation will wait after the first message to send the reminder, and what the reminder message looks like.
You can also chain reminders so that there will be multiple reminders if your customer does not answer to the first reminder. For example, if you add two reminders which are both set to send a reminder after 3 days, the first reminder will be sent after 3 days of the initial message and second one after 6 days.
Wait for answer
There is also a separate Wait for answer step, which allows you to define a wait time after sending message or reminder. As an example, you can define wait time as 7 days so that the next step of the automation won't run before 7 days have passed.
You can also define if the automation should always continue after the wait time, only when answer received, or only when the answer is missing. This way you can filter customers who have or have not answered to the survey in the former steps.