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

Yes

The word "portão" is identical in meaning, spelling, and grammatical gender in both Brazilian and Continental Portuguese. The only differences are phonetic. In Brazilian Portuguese, the vowels tend to be more open and the rhythm of speech is more syllable-timed (more "musical"). In Continental Portuguese, the vowels are often more closed or reduced, and the rhythm is more stress-timed. Additionally, the realization of the "r" can vary depending on the specific regional accent of the speaker in both countries.

Brazilian Portuguese Examples

1. O portão está aberto. (The gate is open.)
2. Eu esqueci de trancar o portão. (I forgot to lock the gate.)
3. O carro passou pelo portão. (The car passed through the gate.)
4. O portão da garagem quebrou. (The garage gate broke.)
5. Pinte o portão de preto. (Paint the gate black.)

Continental Portuguese Examples

1. O portão está aberto. (The gate is open.)
2. Esqueci-me de trancar o portão. (I forgot to lock the gate.)
3. O carro passou pelo portão. (The car passed through the gate.)
4. O portão da garagem avariou. (The garage gate broke/malfunctioned.)
5. Pinta o portão de preto. (Paint the gate black.)