Can I upload a PDF of my W-2 form?

No.  You can key it in or download it if your employer is partnered with TurboTax to make it available for import.  Or if you use the mobile app, you can snap a photo.

https://ttlc.intuit.com/questions/1934390-how-do-i-import-my-W-2

https://ttlc.intuit.com/questions/2588751-why-can-t-i-import-my-w-2

https://ttlc.intuit.com/questions/2938482-how-do-i-take-a-picture-of-my-w-2-in-turbotax-online

This is most frustrating thing with Turbotax...to key in each and every value from standard W2 form into Turbotax.

Can't you extract the content from W2 form with Optical Character Recognition (OCR) software? 

Regards,

Krish

No.  If you use the mobile app you can snap a photo of a W-2.  Or some employers are partnered to allow you to import it.  Otherwise you need to key it in.  It takes a couple of minutes.