The maximum number of Jenkins jobs is dependent upon what you set as the limits in the master and slaves. Usually, we limit by the number of cores, but your mileage may vary depending upon available memory, disk speed, availability of SSD, and overlap of source code.
For the master, this is set in Manage Jenkins > Configure System > # of executors
For the slaves (nodes), it is set in Manage Jenkins > Nodes > (each node) > Configure > # of executors