Drinking is part of business in China. You can only either do it or not. If you once started, you can not tell them that you do not drink.
But you can drink according to your rules - you are laowei
So, if they want to drink with you tell them, you only do gambei with all together - not each in a row. And then, after a few beers, many will already give up because they are not used to it. And you also do not have to do gambei all the time. You can also just banbei. Or simple Yidiandian.
They will follow you, do not worry. Although they always search for a way to drink with you alone - stay hard and do not allow it. I did this already many times - never lost a battle
And if you do not want to drink at all, you can still excuse by saying your stomach is not well today. This will be accepted. But do not drink afterwards and get seen. This will make you lose face.