It is possible to track the behavior of your customers through Google Universal Analytics tracking
However, this is restricted only to redirect orders. If a customer reaches the MultiSafepay payment page, the UA-code will be loaded and you will be able to see that in the corresponding HTML.
For direct orders (e.g. iDEAL direct, some cases of Klarna, AfterPay, etc.), there is no tracking available, as customers will not pass through a MultiSafepay page after checkout and before the successful payment page.
We are currently working on updating the documentation on Google Analytics to accommodate as many of your possible queries as possible. Please check again soon!