Levels:

Good news! We've recently increased the maximum number of levels that can be achieved in Zynga Poker. The maximum level is now 4275 in web and mobile app versions.

XP: 

The maximum amount of XPs that can be gained per day is limited to 140,000. On average, active players may need to play around 1000 to 1400 hands to reach this limit. 

** Keep in mind that XP multipliers from bonuses and purchases can have an impact on how many hands you will play before reaching the daily XP limit.