From Apple’s press release:
Apple today announced that John Giannandrea has been named to the company’s executive team as senior vice president of Machine Learning and Artificial Intelligence Strategy. He joined Apple in April 2018.
Giannandrea oversees the strategy for AI and Machine Learning across all Apple products and services, as well as the development of Core ML and Siri technologies. His team’s focus on advancing and tightly integrating machine learning into Apple products is delivering more personal, intelligent and natural interactions for customers while protecting user privacy.
For what it’s worth, Giannandrea already reported directly to Tim Cook.
You can tell a lot about Apple’s focus by who is on their leadership page. Aside from the more typical corporate roles — CEO, COO, CFO, and Chief Counsel — the rest of the executive team can tell you almost exactly what the company makes, how they sell it, and what they think is important. By that logic, this promotion indicates how valuable they see Giannandrea, as well as machine learning more generally.