QT (pronounced the same as "cutie") is the stage name for Hayden Dunham.
She is a musician who has released one song called "Hey QT". This song has a catchy tune and is deemed as great by many but awfully intolerable by others. The entire song is secretly an advertisement for a mysterious drink (apparently an energy drink) called DrinkQT that is revealed at the end of the music video for the song. The fact that the entire song was made for the drink can only be known if the music video is watched, as the lyrics are ambiguous.
The name QT itself actually stands for Quinn Thomas, which is apparently her real stage name.
QT is used as a play on the term "cutie" which is useful in her music video.
There is a lot of mystery surrounding this artist and the drink, and she offers a link to purchase her drink online.
She graduated from New York University's Gallatin School of Individualized Study with a bachelor's degree in 2011.