Bitcoin is not using any gas. Rather, using miners fee as fees to the transactions.
Be reminded also that sometimes some exchanges set the own fee for your bitcoin withdrawals.
It's not good for small time traders cause the fee is way too much.
Sroring bitcoins/funds on exchanges is dangerous.
It's always at risk to be lost if someone stole it by hacking the exchange.
If you want to store, then store it where you control the key.
Remember, not your key, not your bitcoin.