According to his LinkedIn page (via Neowin), Holtman left his position at Microsoft in January. Neither Microsoft nor Holtman himself have confirmed the departure.
Holtman previously served as the Director of Business Development at Steam platform developer Valve, leaving his position during a round of layoffs last year. We've contacted Microsoft for confirmation of Holtman's departure, and await a response.
[Update: A Microsoft spokesperson responded to our request for comment, stating the following: "We can confirm that Jason has left Microsoft and we're grateful for his time at the company. We wish him the best in his future endeavors."]