It doesn't make sense, it looks like someone was trying to impressed you, and did not spoke Portuguese, so they used an online translator or this person use very bad grammar. The latest could be true, specially if is a young person that use chat rooms daily.
I try to decipher what it mean, but I could only decipher the begin.
I think it should have being, É muito gostosa gatinha.
Which would be This girl is hot/gorgeous. Gostosa is an Brazilian slang.
I change gachina to gatinha, because it sounds like it is what he meant to say, as the chi in English sounds almost like the TI in portuguese, and having that word makes sense. There is no such of word as gachina, as far as I know, there is also not debe in Portuguese.
The rest of the phrase is really out of order, I try my best to make sense of what it is but I couldn't.
The other words in the phrase are.
Minha=my
namorada=girlfriend
casa=house