Yes, you can use soy milk, almond milk, or skim milk as a substitute for regular milk in magic cake. However, the texture and taste of the cake may vary slightly depending on the type of milk used. Soy milk and almond milk may result in a slightly nuttier flavor, while skim milk may produce a lighter texture. It's important to note that the fat content of the milk can affect the richness and density of the cake layers, so adjusting the amount of butter or oil in the recipe may be necessary to achieve the desired results.