This statue can only be created by using an Obsidian Knife four times in a row on an Ice Cube. The ice cube has a very high of chance to break during the sculpting attempt.
Research shows that the ice cube has a 30% success rate on the first attempt, a 20% success rate on the second attempt, and a 10% success rate on the third attempt. The success rate on the final attempt is yet to be determined, but it is assumed to be approximately 5%. According to this research, there is roughly a 0.04% chance (1 out of 2500) of carving an ice mammoth from any given ice cube, but 9 time out of 10 you will need anywhere from 1600 to 5500 ice cubes.
See also:Ice Cube/Sculpting Statistics