In 2011, there were 2,585 boys named Elliot/Elliott/Eliot/Eliott/Eliut/Eliotte and 635 girls. That's about 4:1 in favor of boys.
Compare that to 2005, when there were 1,537 boys and 215 girls named Elliott/Elliot/Eliot. That's a ratio of more than 7:1 in favor of boys.
Long story short, Elliot is still used predominantly for boys, but the gap is shrinking fast.