Sign into your account at switchrewardcard.com and go to your nodes by clicking "Rewards" in the top right.
This will show you how many nodes are online and running.
You can also navigate to this information via the Switch Web App by logging in and clicking on the "Rewards" tab on the top right.
Per screenshot, see that 1 Smart Node counts as 1 Node online and up to 100 Lite Nodes count as 1 Node online. If this is not the case, check to see if all the steps you've taken were correct. If you continue to have issues, please reach out to the Support Team.
If you are running your node on Vultr you can check to see if it is online by following this FAQ.