Yes. I assume you mean difficulty level. There shouldn't be a stat increase from increasing your own soul level.
1, 1.5, 1.7, 2, 2.2, 2.5, 2.7, 3, 6, 7 times for max hp, attack, magic, agility.
1, 1.5, 1.7, 2, 2.2, 2.5, 2.7, 3, 3.5, 7 max mp
1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 3, 4 for defense and magic defense.
1, 1.5, 1.7, 2, 2.2, 2.5, 2.7, 3, 3.5, 4 for luck
1, 1.5, 1.7, 2, 2.2, 2.5, 2.7, 3, 4.5, 6 for soul drops