Does getting a GED count as a student on tax return.

Simple answer : no.  Working on a GED does not count as being a full time student for purposes of the dependent test.

But, taxes aren't simple.  As others have said, if your pursuit of a GED involved enrollment as a full time student in an eligible institution for parts of 5 months, then yes. 

Furthermore, There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, student status, a relationship test and residence test. Only a QC qualifies a taxpayer.

A child of a taxpayer can still be a “Qualifying Child” (QC) dependent, regardless of his/her income, if:

1. He is under age 19, or under 24 if a full time student for at least 5 months of the year, or is totally & permanently disabled
2. He did not provide more than 1/2 his own support. Scholarships are considered third party support and not as support provided by the student.
3. He lived with the parent (including temporary absences such as away at school) for more than half the year

A person can still be a Qualifying relative dependent, if not a Qualifying Child, if he meets the 6 tests for claiming a dependent:

1. Closely Related OR live with the taxpayer ALL year  
2. His/her gross taxable income for the year must be less than $4200 ($4150 in 2018)
3. The taxpayer must have provided more than 1/2 his support

In either case:

4. He must be a US citizen or resident of the US, Canada or Mexico
5. He must not file a joint return with his spouse or be claiming a dependent of his own
6. He must not be the qualifying child of another taxpayer