GNS3 itself doesn’t have limitation on the number of nodes you can run into it. The limitation will be your hardware.
If your local machine is not enough you can run GNS3 on a bigger machine locally or on a cloud Provider like Packet.
In order to cross the limitation of your hardware you can use multiple GNS3 server for running the same topology.
An example is Jason C. Neumann running GNS3 in a Raspberry Pi cluster:
NOTEThe PI use an ARM processor it’s not adapted to run x86 code on Qemu. Also since this forum post the interfaces has change.
NOTEThis is not definitive. GNS3 is evolving and contribution are welcomes
First you need to add your servers in the preferences.
And will see the resources usage:
When you create your appliance template choose a remote server:
At the node name step choose a name helping to remember on which server you will run the node:
Create a second template for the other server. You have now two node that allow you to manually dispatch the load between servers.
You can use the server summary in order to know which server as free resources