I don't think he folows a tariqa. However he used to be a murid of a tariqa. Not all scholars follow the approach of Shaykh-and-tariqa based tassawuf. For example you can find Imam Shatibi's letter to Ibn `Abbad al-Rundi, and the discussion of contemporary scholars such as Shaykh `Ali Jumu`ah in Islamica Magazine discussing tassawuf. Imam Zaid however follows the Shadhili-Darqawi tariqa and was a murid of both Shaykh Abdur Rahman al-Shaghouri, and Shaykh Mustafa Turkmani (rahimahumullahi). Was Salam.