The drafts are certainly not a result of Benning's talent evaluation skill. He's one voice in the room and he doesn't seem to be the type to veto his scouts and make the call unless it's close, which shouldn't surprise anyone.
A GM can, however, influence the draft in a big way in terms of asking his scouts to identify players with certain skillsets, valuing certain skillsets/traits over others, overhauling the scouting staff, including bringing in a new director of amateur scouting, allowing the team to draft Russians, wanting to draft goalies using a high pick etc. These things can make a difference. For example, Gillis' "moneypuck" philosophy of not dismissing older prospects who were on a seemingly steep development curve led the Canucks to draft Mallet but also Hutton. Meanwhile, Benning, Weisbrod, and Brackett rate the USHL highly and you see the Canucks draft players like Gaudette and Madden who they thought had underachieved at the USHL level.
Part of the GM's job is to evaluate his staff. I expected Benning to properly evaluate his scouting staff and it looks like he did and made the changes he wanted to make. Gillis did too and made changes but by his and Gilman's admittance they made changes a bit late.
In the same vein, a GM may actually not have a bigger influence on pro scouting as he does on the amateur side. Teams do have a pro scouting staff as well. When Gillis was GM, he relied heavily on Eric Crawford who was initially his director of pro scouting.
