To change the gathering, taming and XP multipliers you're going to need to add the following inside the GameUserSettings.ini under Configuration Files in the server control panel:
HarvestAmountMultiplier=2TamingSpeedMultiplier=3XPMultiplier=2
Paste the above lines within the [ServerSettings] section.
The values above are higher than the default ark settings, which will give you x2 harvesting/XP and x3 taming multipliers. You can further adjust them to your liking.
