Reputable breeders never use the word teacup. They will say "small" or let you know that the puppy will stay smaller than normal but they NEVER ever use a catch word like tcup or teacup. Plus a lot of these tiny breeders lie, plain and simple. And if a breeder will lie about something as simple as age, then who knows what other kind of problems you'll end up dealing with in the long run.
That picture looks almost exactly like the puppy a breeder tried to tell me was almost 7 months old. If you look at enough pictures on YT you can easily tell what an adult or older pup should look like. Sometimes it's harder to listen to what your gut instict is telling you rather than your heart though. But if you see an ad from the same seller with two different ages for the same puppy picture, it's pretty easy to know they're not someone you should deal with. Puppies don't double in age in one week
Your friend should try to get her money back asap and buy from someone recommended on YT(even standard size yorkies have smaller offspring, you'll see it many times on here). A smaller yorkie can be just as healthy, it totally depends on where it came from. A good breeder is worth their weight in gold because you know what to expect and you can get a smaller dog if you just wait till nature has it happen. I learned my lesson and hope no one gets scammed or gets a sick puppy but sadly it does happen. You should have your friend join YT, that way if she sees a puppy/dog she particularly likes the looks of she can PM the member and find out what breeder they used. I think quite a few of us have a list of "if I ever get another one....."