The study by Dr. Wang Chun Wei, a lecturer at the business school of Australia's University of Queensland, states that:
"...tether grants were potentially timed to follow bitcoin downturns and subsequent bitcoin/tether trading volumes increased ... However, the impact of tether grants on bitcoin returns were not statistically significant, and therefore tether issuances cannot be an effective tool for moving bitcoin prices."
Furthermore, while bitcoin's trading volume does increase following USDT grants, Wei notes that "you cannot use trading volume to predict price, as the effect is simultaneous. In my paper, I state that past trading volumes do not impact future returns." (Source: CoinDesk)