I would suggest doing these:
Stop listing shitcoins and have a dedicated team to research and decide which coin is great to list. Voting is great but do not just accept any coin that gets voted up on the list.
Rev up the marketing. Promote the exchange heavily on many social media platform or any cryptocurrency related forums such as this one. Your team could run another bounty campaign to help promote graviex and gain more users/traders. Even if the bounty pool for the bounty campaign would be composed with GIO's, I'm sure more will still participate since the coin is already listed on an exchange and can already be traded. Your team could also place ads on cryptocurrency related websites (might be very costly depending on which website).

They are already listed on coinmarket cap. See here: https://coinmarketcap.com/exchanges/graviex/
As for them making it big like those old established exchanges, honestly, if they continue listing shitcoins, add to the fact that the team doesn't seem to consider executing any marketing to further promote their exchange and attract more users/traders; I doubt it will even happen anytime soon. Don't get me wrong, the exchange is great, even has great feature such as giving back part of their daily profits to the GIO (Gravio Coin) Holders. I just hope they would listen to their users and implement changes.

Look at this coins that they list  
All their listed coins are pure scams, i wouldn't be surprise if this exchange disapear one day.

good day guys, why website is down? please post update.

thank you.

Hi good day can deposit EBS coin plz check it   

Hi! Haw i can reset my Google Authenticator on u exchange? yrdna@mail.ru
My telefone was broken, and now i have a new.