There is no high speed train link between Seville and Lisbon, or indeed between any centre in Spain and Portugal!
The only airline that operates the route, at present, is TAP Air Portugal and prices are quite steep. Vueling.com does not operate this route.
The only real way to travel between the two centres by public transport is by long-distance bus.
For more info, see this recent article on my blog: http://goo.gl/6eM91
