Title says it all, but specifically
Does Wifi get turned off?
How much CPU power is being reduced and how much battery is saved?
Does the graphics card still run when on sleep mode?
What happens when you go to sleep mode in Windows 10
Below are a couple good references to the topic of the question as the title asks:
This uses very little power, your PC starts up faster, and you’re instantly back to where you left off. You don’t have to worry that you'll lose your work because of your battery draining, because Windows automatically saves all your work and turns off the PC if the battery is too low. Use sleep when you’re going to be away from your PC for just a little while—like when you’re taking a coffee break.
Sleep stores the state of your computer in RAM, and so resumes much faster; you’ll be up and running in two to five seconds in some cases. However, sleep uses a fair amount of battery power. So it makes sense to decide which of these you want to use and when. The default settings are, in my opinion, not ideal for most usage cases.
Does Wifi get turned off
How much CPU power is being reduced and how much battery is saved.
Does the graphics card still run when on sleep mode
For the question about the Graphics Card and the WiFi, those are not operational in sleep mode until the PC wakes from the mode.
For the CPU question, that will depend on the sleep state you have configured, see these two resources for more detail on these states:
For the Battery question that depends on many factors as well but see here for a good read:
'Sleep mode' in a nutshell stops the CPU's clocking, so the CPU stops right where it is. The memory is still powered, and everything else does nothing.
When you wake the computer 'up', the clocking starts, and it moves right on.
Because the CPU does not react to interrupts while it 'sleeps' (except the 'wake-up' call), all external access it disabled, so no wireless, no internal clock updating, etc.
yes, wifi is turned off (if your computer is not set up to be awaken remotely from network)
cpu and battery consumption are very low (aprox. under 0,1%)
no, grafics card is shut down
(fyi all jobs that you are running will be frozen till power on. even if you do a heavy cpu work like encoding of the movie)