Crayfish will consume some of the algae but not nearly as much as shrimp or snails. You won't see any noticeable difference with or without. Crayfish are especially usefull for removing dead plant matter, they love to tear apart dead leaves. That's what mine did in my first tank.
If you want to get it off leaves, you need shrimp and snails,
corydoras can help with algae as well. And time.
Here's a picture of my tank going through Brown diatoms starting from 2 weeks after tank start and green algae after some 6 weeks. After 2 months, algae free without intervention from my side except WC. Just shrimp, snails and corydoras are enough.
50% WC the first 2 weeks.
50% WC every 2 days the third week.
50% WC two times the fourth week.
50% WC from 5th week to now, every sunday.
Also, obviously, the more plants you have, the easier algae gets beaten.
day3:
day 27, brown diatoms appearing everywhere:
Day ~48, green algae taking over everything:
A few days ago, no more algae:
