If you are using TurboTax Online, please review the steps below. 

1. Sign in into TurboTax Online.
2. Complete your Intro and Profile.
3. Select Find from the TurboTax menu. Enter your T4 type in the search box, then select Go.
4. After selecting Go, a new screen appears where you can select your specific T4 slip, then Continue.
5. The last step is to enter your slip information, and you're done.

For more information, please review this link below from TurboTax Canada. 

How do I enter a T4 slip

Thank you for choosing TurboTax.