You asked so nicely, but no.

Unless you are one of those people who does not like their cakes at all sweet. If that is the case, well, still no. The consistency and texture will not be right. Sugar adds more to a cake than just sweetness.

There is approximately 1-1/4 cups of sugar for every cup of evaporated milk, when you substitute it for condensed milk. So if you would like to heat the two and stir until the sugar is completely dissolved, then yes, you may use evaporated milk. Without the sugar, however, your cake will be a disappointment.