Depends on what you are calling "heat". EV batteries like it in the 70-90F range. Running the heater, et all, has no impact on the charge capacity of the battery, so don't look at it in that way. Someone told you some incorrect information. Range and capacity are two completely different factors. Capacity is measured in kWh, while range is in miles. A certain number of kWh will translate into a number of miles that can be driven. But unless you have the battery set in the car's settings to charge to less than 100%, you are charging to full capacity every time.I am thinking that the range will get worse from our heat. I was told to not run my heater, ac, and seat warmers to increase my charge capacity.
Yes, running the heater will drop your range at least 25%, depending on the outdoor temperature. If you have the cold weather package, which adds a heat pump, that range drop might be 20% or less. Running A/C might be 10-15% range drop, at most. I never really noticed any loss of range in my Niro PHEV or my Bolt from A/C use. Seat and steering wheel heaters use very little power, and depending on your personal body functionality might provide all the warmth you need on many cooler days. Assuming they can provide all the heat you need, and it's not really too cold outside, I would rate them at maybe 10% range loss and the outside. Probably closer to 5%. Also, if you're traveling for some time and not getting into and out of the car (and therefore not opening the door often), once you've used the heater to warm the car's interior it takes very little power to maintain that warmth. On my Bolt, where I could see the amount of power coming from the battery, the heater would start out using 7+kW of power. But once the car interior warmed it would drop to 2-3kW, hardly any more power than the A/C uses. So if you can pre-warm the car while it's still plugged in (therefore using house power to heat the car, not the battery), there will be vert little range loss from using the heater.
Your battery is around 64kWh. Assuming you are driving at a consumption of 4 miles/kWh, that should translate into 256 miles. 4 miles/kWh is easily doable, unless you're always driving at freeway speeds and/or have a lot of hills (or really have a lead foot). But remember, you never actually drive the car to zero battery, so real world you're maybe going to get about 230 miles. Increase your driving efficiency, and you range increases for the same amount of battery capacity.
As we've explained, your range with that given amount of power (kWh) will vary based on numerous factors. Cold weather is the largest impact, not only because of heater use but cold also reducing the battery's efficiency. The car also uses some battery power to warm a cold battery, so that too impacts the total range. The next major issue with range is your most recent usage. If your last drive was at freeway speeds over a mountain pass, the computer is going to base your expected range on you continuing to use that same level of power. If instead you are only moving slowly around town, with little to no changes in elevation, you might even see your estimated range increase for a while. I've seen an extreme case of that when I had my diesel Passat. I could fill the tank and show about 600 miles of range. I then get on the freeway and cruise along at 65 MPH in steady traffic and flat ground, and in 30 minutes my estimated range has climbed to 750 miles. This is all because the computer has recalculated how far it thinks I can drive based on the latest consumption figures.
What is your car reporting for consumption? Somewhere on a screen there will be a miles/kWh number, and that will provide a good idea on your power usage. If it's less than 4 miles/kWh, my guess is you are driving at higher speeds, experiencing a lot of elevation changes, or perhaps both. I live on a big hill. I could drive somewhere and be displaying 4.5 miles/kWh before climbing back up the hill, but that short climb would drop my average down to 3.5, and maybe lower, all depending on the conditions at the time. EVs are going to have a much wider variation in power consumption compared to an ICE, but it often swings to the favor of the EV, again all depending on the recent driving conditions.