Flow

Hmmm, I'd say this depends on whether you actually have the link or not. Links in flows support merge fields, so if you were to add a display text to a screen and create a link inside it, you could use a formula resource to generate the actual URL. To do this, use regular merge field format:

{!my_formula_name}

But the question is what kind of survey tool you're using and whether your flow can actually get the link to it.