I am making printer room and I want to show how many printers are running in another room.
the idea is to make a lamp with a 7 segment display next to it.
When one are running display shows 1 and when two printers are running display show 2 and so on. Same time lamp is on.
When printers are ready display is 0 and lamp is off.
Can I somehow use some plugin to control the 7 segment display and lamp.
Hope someone get my point 
Is this for a printer farm at a business?
No this is for home use. The lamp informs other people in the house that printing is in progress and they know you can't go there and the display is just for fun next to it.
I don't have the room or the budget for 7 printers 
, just out of curiosity, why can't other people in the house go there?
It is recommended to use one OctoPi / OctoPrint (i.e. one RPi) for each printer. There are existing plugins that will communicate with other services (IFTTT, MQTT, Slack, etc.) so I would suggest you use one of those on the OctoPrint systems and the another RPi (or similar) to drive your lamp and seven segment display.
Personally, I would use the TP-Link Smart Plug or similar hardware to rig up some things (like the lamp). The TPLinkSmartPlug plugin might help.
For the LEDs, you'd be looking at something like this as combined with the OctoPrint-PCA9685LEDStripControl plugin.
I do not have either. I have two, but maybe expand more. The room is for me and my dad. If I put the camera to record my print, no one will move the camera because the room is small. 
If you have any arduino experience, it would be easy to set something up using MQTT and something like an ESP32 to trigger a relay and drive the 7 segment display. It will require installing a broker, but if you have a farm setup then you have the resources to make it work.
yeelight light bulbs work also great
you can control them by pushing a .json to their ip address.
there was a plugin which makes it easier.
I made a shellscript for each state which fired the json and octoprint triggered the scripts.