How much tip I could earn every node? I have 5 unused vps that is payed for 2 years.
I don't know, depends on a few factors like stability, speed, exit/relay node etc.
From the website:
Using the options above you can filter the set of relays that you would like your donation to be sent too. Your donation will then be divided among the relays listed below according to their Donation Share. The donation share is proportional to each relay's bandwidth contribution to the Tor network. If the share of your donation to an individual relay is too small it will be redistributed to other relays.
Don't expect to earn back your costs, it's not effective. But since you paid for them anyway, you might be lucky Satoshi donates a few 10k satoshi to us
