Note: This is not significant as an LNG tanker. It is a LNG Terminal. This means that LNG can be transported to this ship and it will vaporize the LNG for pipeline transfer. The gas will be transported via pipelines inside Finland but also to Estonia and probably other countries.

Very rough estimation would be a bit less than a month if we were still in 2020. However, much of gas consumption has disappeared. Gas is not a significant part of Finnish energy sector. Most of the gas is used in industrial applications with industrial level bakeries being a big consumer. Most of these have moved on to different energy sources after the war. The consumption dropped 50% just in 1st half of 2022. So I would assume that we are at max 25% of the level we were in 2020 which would suggest that this gas lasts multiple months at least.

Edit: I forgot to add the actual point of this ship. This ship isn't really a tanker for LNG. It is a hub for LNG. This ship will remain in the harbor while other ships fill its containers with LNG depending on need. I have seen estimations that it would be filled every 2 weeks since this ship will deliver LNG to Estonia through the pipeline from Finland to Estonia.

If Russia continues on this path, I doubt the relations will ever be normalized. If they change their path, it will still take minimum 10 years for countries like Finland and Estonia. Germany will sell their soul again the first chance they see though.