Arnold 4.0.16 added photometric lights, which can use IES light profiles.

Arnold does not support IES lighting profiles [generally, IES profiles are not used a lot in film/VFX work]. Most of the time, you can do what an IES light does by using an appropriate gobo (aka a slide projector). For example, SHED used gobo lighting in place of IES on their recent IGA Aide Gourmet spot.

SHED created their own gobo filters to create a similar look to IES lights