It usually isn't, Chairman doesn't involve day to day supervision and decision making.
replyWhen Eric Schmidt became chairman or Ruth Porat became president, this was more a transition towards less involvement than an increase of impact.
He means the chief scientist part. Before Demis had no influence on cloud, tpu development, day to day dev tools, etc.
replyDemis took Jeff former title. (Jeff became Chief Scientist when Brain was dissolved into deepmind)
replyI suspect the SVP/CEO leading Deepmind has a lot more sway over the rest of the company than someone with a title and no reports. :)
(Also the 20y+ of contributions and having built much of the base Google infra probably gave more influence to Jeff than the remaining title)