Is the word olha the same in Brazilian and European Portuguese?

Yes

The word "olha" is identical in meaning, grammar, and spelling in both Brazilian and Continental Portuguese. It is the third-person singular imperative (or second-person singular, depending on the pronoun used) of the verb olhar (to look). The only significant difference is in pronunciation. In Brazilian Portuguese, the "o" is typically more open ([ˈɔ.ʎɐ]), and the syllable is pronounced with more weight. In Continental Portuguese, the "o" is often more closed or reduced ([ˈu.ʎɐ] or [ˈo.ʎɐ]), and the rhythm is more staccato.

Brazilian Portuguese Examples

1. Olha só esse carro novo! (Look at this new car!)
2. Olha, eu não concordo com você. (Look, I don't agree with you.)
3. Olha o que você fez! (Look what you did!)
4. Olha, se você quiser, eu posso ir. (Look, if you want, I can go.)
5. Olha a chuva que está caindo! (Look at the rain that is falling!)

Continental Portuguese Examples

1. Vê só este carro novo! (Look at this new car!)
2. Olha, eu não concordo contigo. (Look, I don't agree with you.)
3. Vê o que tu fizeste! (Look what you did!)
4. Olha, se quiseres, eu posso ir. (Look, if you want, I can go.)
5. Repara na chuva que está a cair! (Look at the rain that is falling!)