Which box of your T4 are you trying to enter the 10 million?
Wages
Just to clarify so box 14 on your T4 has the sum of over 10 million. Or is this on a T4A?
T4
Use more than one T4 slip entry. All you need is for the amounts to show correctly on the T1 and the schedules.
TurboTax is suitable for all types of tax returns ;
https://turbotax.community.intuit.ca/replies/2647875