With two matches remaining, Russia have 11 points more than third-placed Cyprus and 12 more than fourth-placed Scotland, who thrashed San Marino 6-0 at a poorly attended Hampden Park in Glasgow.
Belgium had already secured their place at the finals but Roberto Martínez's team stayed perfect in qualifying with a 2-0 win over Kazakhstan in Astana.
Michy Batshuayi scored in the first half and Thomas Meunier wrapped up the win in the second, giving Belgium their eighth win from eight games. The Belgians have scored 30 goals and conceded just one.
Nikola Vlasic scored early to put Croatia on course for a win that would have secured qualification. Bale's equaliser in first-half injury time denied the visitors — including Real Madrid teammate Luka Modric — and kept alive Welsh hopes of qualifying.
Croatia lead Group E by two points from Hungary, who defeated Azerbaijan 1-0 in Budapest thanks to Mihaly Korhut's early strike.
Ilkay Gundogan scored twice and set up another for 10-man Germany to beat Estonia with three second-half goals in Tallinn.
Emre Can, filling in at centre back, was shown an early red card for bringing down Frank Liivak, who would have been through on goal. Germany had never before had a player sent off so early.
- AP