What sentence would a 17 year old receive if charged with a DWI and vehicular homicide?

It depends on the state and county you live in. Homicide is a state crime, so it varies.

Since he/she is 17, he may be charged as an adult. Even if charged as a child, they may be in jail for about 1 year for DWI and about 5 years for the homicide. Once again, it depends on your state.
The juvenile could be tried and sentenced in juvenile or Family Court, or can be transferred to adult court where he could receive time in prison.