Complex sentence: Her influences were Madonna and Olivia Newton-John, though she has often stated she admires Elton John and Billy Joel as favorite artists and was asked and did sing and perform live with Billy Joel and John at Elton John's Madison Square Garden show.
Split into simpler sentences: Her influences were Madonna and Olivia Newton-John, though she has often stated she admires Elton John and Billy Joel as favorite artists. Gibson was asked to, and did, sing and perform live with Billy Joel and John at Elton John's Madison Square Garden show.