The subject of Qigong is a difficult one to come to terms with on many levels though we live in a time in which it has become very popular again, both in the West and in China.
I won’t try to summarize any aspect of this exercise/meditative umbrella of practises except to say that many taiji teachers have said that our discipline is not a form of qigong and that such supplementary exercises are not useful to developing any of the six Family styles of taijquan and their attributes.
One of the exceptions to this is the practise of standing quietly for extended periods of time [5-30 minutes] before and/or after doing any of the traditional Yang solo forms. Since I am, foremost, a Yang style practitioner, I will let one of the acknowledged masters of that art voice his opinion on this from "The Essence and Applications of Taijiquan" by Yang Cheng fu  , translated in 2005 by Louis Swaim and published in 2005. It summarizes neatly the Yang Family approach to standing still as being an integral part of learning and practising that discipline
43+ Years of Experience Training in the Chinese martial arts; 33+ years experience teaching taijiquan and 24+ years experience teaching baguazhang