Any gains made to assets inside of the account are tax free. So if you put in $4k worth of stocks one year and they increase in value by 1000%, that's still all

Any gains made to assets inside of the account are tax free. So if you put in $4k worth of stocks one year and they increase in value by 1000%, that's still allowed by the TFSA rules. If you never contributed at all and were starting today, that is when are restricted to the cumulative amount.