It is hard to say without seeing the sheet music. Usually this one is transposed to D major for guitar and definitely involves the top two treble strings; so no idea what your version would even look like. However, usually if you have consecutive notes on different strings, one per string (i.e. arpeggio-like), you would play just the lowest (in pitch) one with your thumb, and the rest with i,m,a fingers. In classical guitar it seems playing consecutive strokes on different strings with the thumb is not very common if there are alternatives involving the other fingers of the right hand.
1982 Anselmo Solar Gonzalez