You can't snap a
photo of your W-2 in TurboTax Online, nor can you upload a photo you took with
your device's camera. However, you can
take a picture via the mobile app, which will then upload to TurboTax Online.
Please see this link for more details.
https://ttlc.intuit.com/questions/2938482-how-do-i-take-a-picture-of-my-w-2-in-turbotax-online