After all G.I benefits are used what type of funding is available to get continue on to get a master’s degree?

In addition to the steps LTC Eugene Chu mentioned (especially joining the National Guard*), check with your state's Veterans Affairs Office to see if there are state programs/scholarships available for veterans residing in that state.

There are many resources to find scholarships for veterans*, you just need to do some creative internet searching.

If you have a disability rating of 10% or more from the VA, you might be eligible for VR&E if a Vocational Rehabilitation Counselor determines you need it.
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* Many states will fully fund a bachelor or graduate degree at a state university if you belong to the state's National Guard.
* https://www.bestcolleges.com/resources/military-veteran-scholarships/
* https://www.dvs.virginia.gov/wp-content/uploads/2021/01/Veteran-Scholarships-and-Grants-1-19-21.pdf

Veteran Readiness and Employment (Chapter 31), formerly Vocational Rehabilitation maybe:
https://www.va.gov/careers-employment/vocational-rehabilitation/

I faced the same situation. In my case, as long as I was enrolled in an approved university or college and pursuing a higher level degree . . . no problem, I got the rest of my months. That was my experience.