It is very much a grey area. It says "What happens if you have an existing residence permit?
If you already have a residence permit that continues beyond 10th April 2014, this will continue to be valid, because you have applied for, and paid for residency, and permission has been granted by the Turkish authorities. You have got permission to reside in Turkey until the expiry date shown in your ikamet." but it also says " With short term residency, if you stay out of Turkey for more than 120 days, your residency permission will be cancelled.".