Yes, you can, with the following limitations:
The form Datum must be open in form view when the query runs, or you'll get an error.
You would not use the pound signs (#) in this context. They are only used to indicate a date value when the date is specified as a literal (e.g., #2/3/03# instead of just plain 2/3/03 or "2/3/03"). Here, you're not using literals but references to controls on a form - if the contents of those controls are to be interpreted as dates, then use the following syntax:
Between DateValue(Forms![Datum]![tre]) And DateValue(Forms![Datum]![fyra])