Once a ski resort is running all lifts, with a full patrol schedule, full grooming schedule, and making snow across 100% of the system, the costs would be about maxed out (ignoring the chance of on-off events such as breakages etc.). The revenue, on the other hand, is tougher to calculate. Season passes, period passes (like a 10 of 14 day pass) and non-dated offers would have to be smoothed out across the season / period, then daily tickets get added to the equation. Extra revenue would "go to the bottom line" on a cash basis, but there are intangibles such as the depreciation and amortisation of plant and equipment to consider, along with off-season costs (maintenance of plant and equipment, roadworks, cutting new trails, capital upgrades etc.) and a bunch of other stuff.
Looking at it on a cash basis for a single day or a weekend is one thing, and would be interesting, but the story is more complex, as you'd expect.