The correct term for NASH is Non Alcoholic Steato Hepatitis. This can lead to cirrhosis which is a serious condition involving damage and scarring of the liver that can eventually impair liver function significantly.
Most cases of NASH are related to a process that involves fat tissue invading the liver. The same damage to liver tissue that is seen in alcoholics is seen when this process takes place even though a person may consume little or no alcohol at all. Instances of NASH have increased significantly over the past 5-10 years. This is thought to be related to significant increase in obesity seen in the American population.
If you are overweight, particularly if you carry your weight in the mid section, then the number one most important thing for you to do is lose the weight. Implementing an aggressive dietary and lifestyle modification plan to help you shed excess pounds is the best way to stop this process from progressing.
With that said, Acai berry is a potent antioxidant which can be very helpful in maintaining optimal health. Although I think a potent antioxidant would be good for your health, I do not think Acai alone can have a significant chance at improving your current diagnosis of NASH.
You may want to consider some other natural products that are more specific to liver health such as milk thistle, turmeric, phosphatidyl choline and artichoke extract. These have shown some ability to reduce scarring and damage to the liver in certain situations. However, keep in mind that if excess weight is your main issue, these natural supplements and herbs will not offer a magic bullet to fixing your situation.