Don't know if you're still looking for this, but on the 1870 Rusk Census, I did find your family listed as GATSON.

1870 Rusk Census
Pg 312 Pct 5 Rusk Tx
Albert Gatson 60 Farmer SC
Lettie 41 GA
Martha 23 GA
Robert 14 TX
Victory 7 TX (1863)
Helena 5 TX
Eliza 2 TX

Nothing on Amos Johnson however in 1870. I am researching a connection between Amos Black and Jennie Reid. Her sons Isaac and Dave Reed/Reid have Johnson family members living with them on the 1900 Census.