Each player gets a referral code which can be entered before you do the tutorial. This referral code allows a new player to get 1000 gold at the end of the tutorial. It doesn't matter which existing player's code you put in, the new player gets 1000 gold and the existing player gets 200 food.
Start the game, then choose "Menu" then "Profile". Tap the red arrow at top-right corner of screen then select "Update Status". Finally, activate the following cheats by entering the corresponding codes: