In Splendor can we have more than 3 joker (gold) tokens in our hand without spending them?
Yes, you can have more than 3 joker tokens.

In the list of things you can do on a turn, the rules say:


  
  Reserve 1 development card and take 1 gold token (joker)
  


The rules later restrict when you can reserve a card:


  Players may not have more than three reserved cards in hand


There is no mention of a limit on the number of jokers*. There is only a limit on the number of reserved cards in hand.

*Note that jokers do still count towards the normal 10-token limit. If you are at 10 tokens already, you can still reserve a card and take a joker, but you will then have to discard a token to get back down to 10.