In automations you can send reminder with the "Send reminder after" -step.
Reminder will always have to come after send message step. Send reminder after will define the time period after which reminder will be sent and reminder message the message that will be sent to the customer. Survey will define the survey that will be used in the reminder and it should match the survey in the send message step.
You can also chain send reminders so that there will be multiple reminders if your customer does not answer to the first reminder. If you add two reminders which are both defined as Send 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 -step
There is also separate Wait for answer -step available 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 wont run before 7 days have passed.
You can also define if the automation should continue after the wait time always or only when answer received or only when answer missing, so that you can filter customers who have or have not answered to the survey from the further steps.