Voldemort made 7 pieces of his soul by making Horcruxes. Did it affect his power?

Was his power 7 times greater than the movie before the attack at Harry's parents at Godric's Hollow?

No, the Horcruxes didn’t affect his magical power, just his soul.

Creating Horcruxes splits the soul, but has no effect on magical power. Dumbledore explains that, though the Dark Lord’s soul is damaged beyond repair, his brain and magical power remain intact.

“Without his Horcruxes, Voldemort will be a mortal man with a maimed and diminished soul. Never forget, though, that while his soul may be damaged beyond repair, his brain and his magical power remain intact. It will take uncommon skill and power to kill a wizard like Voldemort, even without his Horcruxes.”
_{^{- Harry Potter and the Half-Blood Prince, Chapter 23 (Horcruxes)}}

As Dumbledore said the Dark Lord’s soul was diminished but his magical power remains intact, that shows making Horcruxes didn’t affect his magical power, since otherwise it couldn’t have been described as remaining intact, since he’d made several Horcruxes.

It is not mentioned whether he became more powerful

Voldemort mentioned in a discussion with Slughorn the possibility of seven as a powerful number. But only six real horcruxes were produced:

• the diary


• the ring


• the locket


• the diadem


• Nagini


• the cup

The other "pseudo-horcruxes" Quirrel and HP were no real horkruxes since the necessary horcrux magic was not executed.
Thus, there were always only six real horcruxes -- never seven. Hence, we do not know the answer whether he gets more power. The "less powerful" part was explained by @Bellatrix.