It is dangerous to overload a motorbike lift stand above its maximum load capacity. Many ATVs are much heavier than bikes. It is important that you consult the manufacturer’s handbook that came with your ATV to get an accurate figure for its weight. Remember that if you have modified it in any way it may be heavier.
If you are going to use a lift for an ATV it is important that you choose one that is specifically designed to lift an ATV safely.