Proper hydration is essential for all aspects of health (skin health included!) but ingestion of water doesn’t mean skin hydration. How supple your skin looks have more to do with sebaceous gland density and skin-barrier function. Some people drink plenty of water and still have dry skin and others don't drink it that much and still have skin that looks relatively moisturised.⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀ Having said that, water does help your complexion by allowing the entire body to effectively carry out the functions that flush toxins and keep fluids moving through your capillaries. Drinking plenty of water helps to improve circulation to the skin and toxin removal from the skin. Dehydration and skin hydration levels do correlate sometimes though, only in extreme cases.
The conclusion is: drinking more water won't necessarily mean that your skin will appear more hydrated, but it will help your body fight other factors that cause skin concerns.