What types of benefit a steemit user get from a witness after voting them?

Steem witness voting has no direct impact or other correlative factors that might impact a new users growth. Witnesses don't provide any services that is mutually exclusive to individuals. However steem witness voting is passively benefiting to every steem user at a broader sense.

Steem blockchain runs on a protocol named DPOS-Delegated Proof of Stake. Using this witnesses create blocks which makes the steem blockchain. Now their work is somewhat similar to a bitcoin miner. They mine and produce blocks and they are rewarded with a percentage of that block as Steem power. They keep running nodes every single second..If steem blockchain was in the hands of a selected individual it wuld have caused a centralization and they could have manipulated steem blockchain. But elected individuals in this case witnesses are like a democratic government who takes decisions about how the blockchain should behave.

Now you might think how and why witnesses are not centralized. The blockchain woks in such a way that everyone gets a chance at producing a block as the production is allocated randomly. But the higher votes the witness has the more trusted he/she is to the system. So voting an witness is not about a gain or a loss directly. Its to ensure that our beloved steem blockchain is in capable and authentic hands.