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

Yes

The difference between "dias" in Brazilian and Continental Portuguese is purely phonetic. In most Brazilian dialects, the "s" at the end of the word is pronounced as a voiceless alveolar sibilant [s] (as in the English word "sun"). In Continental Portuguese, the "s" is typically pronounced as a voiceless postalveolar fricative [ʃ] (as in the English word "shoe"). The spelling, meaning, and grammatical function of the word remain identical in both varieties.

Brazilian Portuguese Examples

1. Eu te vejo daqui a dois dias. (I will see you in two days.)
2. Esses dias de chuva são ruins para ir de ônibus. (Those rainy days are bad for going by bus.)
3. Eu não vejo ele há muitos dias. (I haven't seen him for many days.)
4. O trem demora dois dias para chegar. (The train takes two days to arrive.)
5. Três dias é pouco tempo para essa tarefa. (Three days is too little time for that task.)

Continental Portuguese Examples

1. Vejo-te daqui a dois dias. (I will see you in two days.)
2. Estes dias de chuva são maus para ir de autocarro. (These rainy days are bad for going by bus.)
3. Já não o vejo há muitos dias. (I haven't seen him for many days.)
4. O comboio demora dois dias para chegar. (The train takes two days to arrive.)
5. Três dias é pouco tempo para esta tarefa. (Three days is too little time for this task.)