It is never stated that Horde died eight to one compared to the Night Elves, no. At best Saurfang made this analysis when the Horde made it to Astranaar:
- Malfurion struck hard all across the Horde’s lines, killing those foolish enough to charge into battle with him. When the final numbers were tallied, there would be more slain Horde than kaldorei.
But Saurfang had anticipated that. He didn’t like it, but when you threatened an enemy’s home and invaded their land, you paid a certain price.