No, not if IE is running on native MacOS. The Qlikview IE-Plugin client is a "Windows binary" and will as such work only on that platform. The Ajax client will probably work on a Mac IE, but depending on IE version, there might be issues.
If they want to run Plugin on MacOS, they need to virtualize a Windows machine on the Mac box and run it through there. Then there might be options in Mac hypervisors (Parallell?) to do things like VMWare call "Unity" - that is to "hide" the Windows OS and only show certain virtualized applications on the native MacOS client.
/edit: Since VMWare is available on Mac, Unity should work there - I think?