The eastern practice of yoga has become quite prevalent in recent years. I imagine that when the Titanic sailed, it was quite rare and exotic. However, England had (shall we say) strong interrelations with India leading up to the early 20th century, so there was certainly some yoga in practice in England. The Titanic was sailing for 4+ days, so if there were any regular practitioners they probably would have used the opportunity. The question really is: among the 2,224 passengers and crew, what is the likelihood that one or more of them practiced yoga regularly?
Introduction of Yoga in earnest to the West only occurred from the late 1920s onwards. The likelihood of any of the few early adopters being on the Titanic is low; especially as no Indian nationals were on the passenger manifest.