The general rule is not to cook with a wine you would not drink. The same is true for what you are attempting. If it tastes rich by itself, it will add a rich flavor to your pate. Unlike baking, there is much room for interpretation in cooking. So using the liquor called for in the recipe will duplicate the flavors of the original. But that doesn't mean you can't use something different. The important step with whatever wine or liquor you use, is to taste it first. If you enjoy drinking it straight, then you can be assured that you will most likely enjoy it in whatever dish you are making. If it tastes awful straight out of the bottle, it will make the food taste awful as well.
Having said that, you would not substitute a sweet white wine in a recipe that calls for a rich red Bordeaux. But you could substitute a different good quality red wine.
Chicken livers, in addition to being forgiving, are also pretty inexpensive. So make the pate with what you can get. Then when you get what you are looking for, make some more. Enjoy the experimenting.