Leverage helps the trader to trade with more than what is available in the trader's account. Lets say I trade long 10 BTC/USD at 7000 USD using leverage of 1:10 (i.e i deposited 7000 USD). Now if the rate increases to 8000 USD I make a profit on 10 BTC/USD. But what if the rate drops to 6000$ then in essence I lost 10000 USD which is greater than my deposit of 7000 USD so I will loose all of 7000 USD. My question is does this gets executed automatically like when the system finds the loss is greater than the deposited amount, one looses all the deposit or the trader have the option to wait in the hope that the rate will indeed increase in future?
The most important thing to understand is that once your deposit of 7000 is exhausted your brokerage firm would be hit by any further losses. You would still be legally responsible for them, but the money would initially be coming out of the brokerage firm's equity. If the price rises on the other hand the profits go to you...
Obviously the brokerage firm does not want to be in such an asymmetric situation (they would be lending you money for free while bearing credit risk from your possible default) and it will be in their economic interest to shut down your trading as soon as possible if you do not put up additional money. In a well designed electronic brokerage this is all taken care automatically by software and your trading will be shut down even before the 7000 limit is reached.
As a trader you will be hoping that "the broker does not notice right away that my capital has been wiped out and the price of BTC soon starts to rise" but as I said that is unlikely and at most brokers the situation is considered an emergency that could threaten the broker's existence (if the price keeps going down and you are unable/unwilling to pay what you owe them). Many firms have gone out of business due to customers' leveraged trading and they are now wise to this issue and will take action to protect themselves (to your detriment).
This is usually brokerage house and/or exchange rule specific.
I can't speak to cryptocurrency brokerages/exchanges, however in the above example more than likely once BTC drops to 6400 you will be getting a phone call requiring you to deposit additional funds into your account. If you do not do so the broker/exchange will liquidate your position at market levels and you will be responsible for any shortfall if the sale price of the BTC is less than 6300.