Is it safe for my 7 week old baby to sleep 8 hours straight thru the night or should I wake her to feed her?

It's fine to let her sleep. She'll wake when she is hungry. Babies can start to sleep through the night that early and it's totally fine. Her little body knows what it needs. Waking her will most likely just make her fussy and she may not feed. Leave her be. She's fine. :)