Nigeria to India via Istanbul

No, there are no visas to be issued at the airport^*. All visas are now issued online ("e-visa") or from the consulate / embassy.

If you are an Indian passport holder, you do not meet the requirements for the e-visa and will have to apply in advance if you want to visit Turkey during your layover:

India: Diplomatic passport holders are exempt from visa for their travels to Turkey up to 90 days. Ordinary, Special and Service passport holders are required to have visa to enter Turkey. Ordinary, Special and Service passport holders with a valid Schengen members or USA, UK, Ireland visa or residence permit may get their single entry e-Visas valid for one month via the website www.evisa.gov.tr, provided that they meet certain conditions.

If you are a Nigerian citizen, the same rules apply:

Nigeria: Ordinary, official/service passport holders are required to have visa to enter Turkey. These passport holders with a valid Schengen members or USA, UK, Ireland visa or residence permit may get their single entry e-Visas valid for one month e-Visas via the website www.evisa.gov.tr, provided that they meet certain conditions.

Source: Ministry of Foreign Affairs Turkey.

^*You could arrive at the airport and use one of the kiosks to get an e-visa, but you would still have to meet the e-visa requirements.