If I delete my gmail will it delete my accounts associated with it like steam or minecraft?

No not at all

Change the email you have on your steam/Minecraft account. Before you delete the email.

What if it is on a website

No, it deletes the address, which will make it so things like steam and mine craft will still try and send you emails but you won't get them. Like moving house your home address changes, just means that you won't get the mail. You can change your email on steam and minecraft. Your email and accounts are not really linked it's just the email is the place where the accounts send mail too. Don't worry if you delete it. Your accounts will be fine. Just make sure to change your account to your new email first, just incase you get locked out if the account sends the deleted email account a password reset.

If you remove the e-mail address associated w/ your other services (like Steam, Minecraft, Netflix, ect.), you will lose the recovery methods should you forget your password OR get locked out of your account.

It's HEAVILY RECOMMENDED that you update the e-mail addresses of services that are using the unwanted e-mail to another address under your control BEFORE closing the unwanted e-mail address.

Along with what other people said, if you want a new email service, consider setting up GMail to auto-forward to your new email instead of deleting it. It really depends on the reasons to delete it, but you could do this while you change the emails.