The question whether Taijiquan (Tai Chi) relates to Qigong in some way is often asked. Here are Master Chen Yingjun‘s words about Qigong, part of and interview conceded to my Gongfu brother Norman Kobow, his student in Germany:

Taijiquan (Tai Chi) in one way is Qigong, because we try to make the Qi flow in the whole body (…)
Qi and the physical body work together: Internal and External working together. So, it is very important that we train the external body too.CHE YINGJUN

In old times, there was no visible separation between Qigong and Taijiquan (Tai Chi), in Chen family training. Laojia, the traditional form, was repeated incessantly by the trainees, and with time, Qigong and its principles became apparent. Grandmaster Chen Xiaowang, when starting to teach seminars outside China, felt the need to select some movements from the forms, and teach them separately. These movements constitute Taijiquan (Tai Chi)‘s Qigong curriculum, Silk Reeling Qigong.
We also practice one still Qigong, called Zhanzhuang, or Standing Meditation. Holding postures has always been practiced in Chen family, but Chen Xiaowang selected this posture for regular practice because it can be held in a higher stance and it is symmetrical, making its understanding easier for the beginner.