If a GA in a group gets less than 5 entries the it also affects the group ratio?

no, but cg will take you out into a small alley and will beat you with a pool noodle

pretty sure it does, its only CV you don't get, it has been a while but the ones I had that didn't get enough I recall giving me the ratio(as it is still gifts given to the group)

You get 0 CV but the price goes up towards your group ratio of "group sent" and "value difference"
e.g 15$ game and less than 5 entries will get you 0 CV, sent +1 game but still a group value +15$

hope that answered your question!

From the giveaways you've made, i can see that if you add more people to your whitelist, it will also help participation so you do regularly get more than 5 entries if this is a concern for you.