Can ultrasound in 5 week will confirm 1 baby or more

In 5 weeks, there is no heartbeat of the baby. The fetal pole also might not be seen, it will be too early to say anything. But you might get an idea if it is a single gestation or twin.

Seven weeks scan can let you know

The first scan will confirm how many gestational sac is there. So after 6 weeks they will take the scan.