I came across similar type of question in Manhattan mock. If you test statement 1 with an x value of 4 and y value of 1 then it holds true. However, if you hold an x value of 1/4 and y value of 1/3 then it doesn’t hold true. Therefore not sufficient.
Statement 2: If you test with values of integers greater than 1 then with a value of x=2, x cube is 8 and if y value is 1 then x is always greater than y. But if you take negative fraction. X cube as -1/8 and y value of -1/4 then given condition holds true but x is less than y.
When you combine statement 1 and 2 then you’ll have to only take positive values of x or fraction between 0 and 1. There x will always be greater than y.
The trick in these question lies in consideration negative fractions and observing how the condition changes. Hope it helps.