well it depends, there is no simple formula. For a vote you get a part of the reward pool based on your amount of steem power in comparison to the steem power of the whole system.
You can use https://steemworld.org/@thenomadictales there you can simulate different SPs
Hey thanks. The link is really helpful. Tried using simulator to get actual figures. Do you have an idea about extra benefits ? How about power to choose payouts.