As right as C4D avenger @SIgor usually is, I must disagree with him on this occasion ! :)
There's no doubt that HDRI on a sky is quick and involves no effort, but I don't think that's what's going on here.
For me, this looks like a typical studio setup, some well placed softboxes*, and fairly standard 3 point lighting, 1 orangey light, 1 bluer, and another white top light. The attractively soft shadows are easy to get if you light this way. You can still use an HDRI for reflections, and use proper lights, but there is no good case for GI here.
CBR
*Softboxes, if you don't know, are area lights, carefully positioned and aimed, made visible to reflection, and use area shadows for most realism.