Answer: an illusory correlation
Explanation: In simple words, illusory correlation refers to establishing a relation between two variables even when no such relationship exists in real.
In the given case, Tuan bought a jacket and due to some events, started believing that it has magical power in it. Tuan do not have any kind of quantitative or relative proof that the commodity have such magical powers or are somehow related to the good fortune but still he believes that.
Hence we can conclude that Tuan is trying to make an illusory correlation.