Most hot water tanks or water heaters last for around 10 to years to 15 years before they start going bad and start leaking and need replaced.
Water heater tanks should be lined inside with either a rubber coating or a glass coating to keep the inside of the tank from rusting through directly from the water.
Still though eventually the tank can rust and leak after so many years of use and if you have a lot of chlorine or hard water the chlorine can be corrosive to the water heater and plumbing and the hard water is not good for the water heater tank either.
If you get 10 to 15 years out of the water heater then you're doing good but if you get 20 years or more you're lucky.
If your water heater is at least 10 years old or older you should budget for a new one eventually because it's just a matter of time that the water heater is gonna go bad and leak.