Have to give you the standard disclaimer that I think it's crazy to bring in pre-aggregated data ... however, I understand their are political forces that are driving you to ask that question.
In this short video I demonstrate that it's not only possible, but incredibly easy to load data from OLAP cubes using MDX. I begin by playing with an MDX query right in the SQL Server Management Console. I copy the query, create a connection inside of Qlik Sense, then paste the MDX Query, and run it. BOOM. Your OLAP data served up inside of Qlik Sense.
Wait you want more? You want to see if I can change the query right inside of Qlik Sense to ensure I'm not pulling out aces that were up my sleeve? Ok, I do that as well.
MDX inside of Qlik? Yeah we've got that. Because we run any native command you can throw at it.